全文获取类型
收费全文 | 1457篇 |
免费 | 156篇 |
国内免费 | 16篇 |
出版年
2024年 | 2篇 |
2023年 | 8篇 |
2022年 | 31篇 |
2021年 | 41篇 |
2020年 | 42篇 |
2019年 | 60篇 |
2018年 | 48篇 |
2017年 | 27篇 |
2016年 | 46篇 |
2015年 | 18篇 |
2014年 | 49篇 |
2013年 | 128篇 |
2012年 | 60篇 |
2011年 | 49篇 |
2010年 | 60篇 |
2009年 | 50篇 |
2008年 | 73篇 |
2007年 | 58篇 |
2006年 | 72篇 |
2005年 | 40篇 |
2004年 | 65篇 |
2003年 | 42篇 |
2002年 | 39篇 |
2001年 | 49篇 |
2000年 | 33篇 |
1999年 | 31篇 |
1998年 | 39篇 |
1997年 | 23篇 |
1996年 | 29篇 |
1995年 | 26篇 |
1994年 | 15篇 |
1993年 | 24篇 |
1992年 | 17篇 |
1991年 | 20篇 |
1990年 | 14篇 |
1989年 | 15篇 |
1988年 | 14篇 |
1987年 | 14篇 |
1986年 | 14篇 |
1985年 | 17篇 |
1984年 | 19篇 |
1983年 | 18篇 |
1982年 | 18篇 |
1981年 | 15篇 |
1980年 | 22篇 |
1979年 | 13篇 |
1978年 | 8篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1973年 | 5篇 |
排序方式: 共有1629条查询结果,搜索用时 343 毫秒
61.
摘要 目的:研究妊娠期母体甲状腺功能减退对胎鼠骨骼肌胰岛素抵抗和线粒体功能的影响。方法:构建妊娠期母体甲状腺功能减退小鼠模型,制备胎鼠骨骼肌线粒体,同时选取健康正常胎鼠做本次实验的对照组。采用酶联免疫吸附法和放射免疫分析法测定两组小鼠甲状腺功能;通过全自动生化分析仪检测两组胎鼠胰岛素抵抗结果;利用Clark氧电极测定密闭反应体系评价两组胎鼠线粒体功能结果,并分析母体甲状腺功能减退与胎鼠骨骼肌胰岛素抵抗和线粒体功能的相关性。结果:两组小鼠甲状腺功能结果、两组胎鼠骨骼肌胰岛素抵抗和线粒体结果对比分析之间均有显著差异(P<0.05)。甲减组小鼠血清中促甲状腺激素(Thyroid Stimulating Hormone,TSH)、丙氨酸转氨酶(alanine aminotransferase,ALT)和门冬氨酸氨基转移酶(aspartate aminotransferase,AST)均较对照组低,胎鼠的空腹血糖(fasting blood-glucose,FBG)、动态3(state3,ST3)、动态4(state4,ST4)呼吸速率和呼吸控制比(respiratory control,RCR)也均较对照组低;而甲减组小鼠游离甲状腺素(free thyroxine,FT4)却较对照组高,胎鼠的胰岛素(insulin,INS)和胰岛素抵抗结果(homeostasis model assessment of insulin resistance,HOMA-IR)也较对照组高(P<0.05)。且母体甲状腺功能减退指标中FT4和RCR、ALT和FBG以及RCR之间有负相关关系,母体甲状腺功能减退的其他指标则与胎鼠骨骼肌胰岛素抵抗和线粒体功能的其他相关指标之间呈正相关关系(P<0.05)。结论:妊娠期母体甲状腺功能减退会降低胎鼠骨骼肌胰岛素抵抗和线粒体功能,影响胎鼠的正常发育。 相似文献
62.
ABSTRACTWe investigated the effects of quercetin (Q) on some hematological parameters and determined the percentage of alpha-naphthyl acetate esterase (ANAE) positive lymphocytes in rats that had been exposed to cadmium (Cd). Thirty male Wistar albino rats were divided into four groups: control (C), quercetin (Q), cadmium (Cd) and Q + Cd (CdQ). Blood samples were taken to assess erythrocytes (RBC), leukocytes (WBC), hemoglobin levels (Hb), hematocrit values (Hct), platelets (PLT), alpha-naphthyl acetate esterase (ANAE) positive lymphocytes. RBC, Hb, Hct; the number of PLT significantly decreased in the Cd group. To the contrary, these parameters were increased significantly in the CdQ group compared to the Cd group. Although we found a significant increase in total WBC count and neutrophil percentage, the number of lymphocytes decreased in the Cd group compared to the other three groups. Also, the percentage of peripheral blood ANAE positive lymphocytes decreased significantly in the Cd group (p < 0.05). Q exhibits positive effects on some hematological characteristics and the percentage of ANAE positive lymphocyte in cases of acute CD toxicity. 相似文献
63.
ABSTRACTHeart attack and oxygen deficiency may cause necrosis in the brain and other tissues. We investigated the histopathological effects of nitric oxide (NO) on ischemia/reperfusion in lung and hippocampus using a rat brain bilateral occlusion ischemia model. Male rats were assigned to sham (SH), ischemic preconditioning (PC), global ischemia (GI) and ischemic reperfusion (IR) groups. Before ischemia was induced, blood was drawn to induce hypovolemic hypotension and for blood gas testing. After sacrifice, samples of hippocampus were harvested. Sections were examined using hematoxylin and eosin (H & E) staining and immunostaining using primary antibodies for GFAP, S100β, iNOS, eNOS and the TUNEL method. Following ischemia, we found evidence of gliosis induced oxidative stress and apoptosis in the hippocampus. No significant differences were detected between the SH and PC groups. In the GI and IR groups, apoptosis and necrosis were observed in the hippocampus. Lung sections were stained with H & E and Masson’s trichrome (MT) and immunostained for iNOS and eNOS. The TUNEL method was used to detect apoptosis. Interstitial edema, vascular congestion, intra-alveolar hemorrhage, perivascular edema, neutrophil infiltration and disruption of alveoli were observed after global ischemia and ischemic reperfusion. Inflammatory cells were detected in the connective tissue. The IR and GI groups exhibited significantly more apoptotic cells than the SH or PC groups. Free radicals, such as nitric oxide (NO), that appear following ischemia and reperfusion in the brain may also injure the lungs. Increased NO in both lung and brain tissue suggests that apoptosis in these organs can be induced by reactive nitrogen species. 相似文献
64.
《Biotechnic & histochemistry》2013,88(3-4):132-137
AbstractWe investigated short (6 months) and long (12 months) term inhibitory effects of low (200 ppm) and high (400 ppm) dosages of acetylsalicylic acid (aspirin) on exocrine pancreatic carcinogenesis. It is known that exocrine pancreatic carcinogenesis can be detected by the presence of atypical acinar cell foci (AACF) in pancreas. We investigated possible inhibitory effects of acetylsalicylic acid in an azaserine-treated rat model. AACF were produced in rats by injection with azaserine according to previous studies. Our findings showed that the number, volume and diameter of pancreatic AACF were reduced after acetylsalicylic acid application. These observations suggest that acetylsalicylic acid may exert a protective effect against neoplastic development of pancreatic acinar cells in azaserine injected rats. Our findings corroborate reports in the literature concerning the effects of aspirin in reducing neoplastic development. 相似文献
65.
ABSTRACTGibberellins are commonly used plant growth regulators that exhibit deleterious effects on various animal tissues. We investigated the histological, immunohistochemical and biochemical effects of gibberellic acid (GA3) on rat testes as well as the possible protective role of pomegranate peel extract (PPE). We used 28 adult male rats divided into control, PPE treated, GS3 treated and GA3 + PPE treated groups. Testis specimens were analyzed for superoxide dismutase (SOD) and catalase (CAT) activity, and examined histologically. We also investigated the androgen receptor using immunohistochemistry. The GA3 treated group exhibited significantly decreased SOD and CAT levels and area percent of androgen receptor. Seminiferous tubules (ST) were widely separated and the germinal epithelium was separated from the basement membrane in some tubules. Areas of vacuolation, degenerated germ cells with pyknotic nuclei and large multinucleated cells were observed. Ultrastructurally, primary spermatocytes exhibited vacuolated cytoplasm, degenerated mitochondria and hyperchromatic nuclei. Degenerated early spermatids with a ruptured or hyperchromatic nucleus were found. Spermatozoa exhibited abnormalities of the head and tail. The cytoplasm of Sertoli and Leydig cells exhibited dilated smooth endoplasmic reticulum. A significant improvement of the biochemical, histological and immunohistochemical alterations was observed in the GA3 + PPE treated group compared to the GA3 treated group. 相似文献
66.
Seeds of Indian ricegrass (Achnatherum hymenoides), a native bunchgrass common to sandy soils on arid western rangelands, are naturally dispersed by seed‐caching rodent species, particularly Dipodomys spp. (kangaroo rats). These animals cache large quantities of seeds when mature seeds are available on or beneath plants and recover most of their caches for consumption during the remainder of the year. Unrecovered seeds in caches account for the vast majority of Indian ricegrass seedling recruitment. We applied three different densities of white millet (Panicum miliaceum) seeds as “diversionary foods” to plots at three Great Basin study sites in an attempt to reduce rodents' over‐winter cache recovery so that more Indian ricegrass seeds would remain in soil seedbanks and potentially establish new seedlings. One year after diversionary seed application, a moderate level of Indian ricegrass seedling recruitment occurred at two of our study sites in western Nevada, although there was no recruitment at the third site in eastern California. At both Nevada sites, the number of Indian ricegrass seedlings sampled along transects was significantly greater on all plots treated with diversionary seeds than on non‐seeded control plots. However, the density of diversionary seeds applied to plots had a marginally non‐significant effect on seedling recruitment, and it was not correlated with recruitment patterns among plots. Results suggest that application of a diversionary seed type that is preferred by seed‐caching rodents provides a promising passive restoration strategy for target plant species that are dispersed by these rodents. 相似文献
67.
《Free radical research》2013,47(10):1233-1238
AbstractThe lipid peroxidation product 4-hydroxynonenal (HNE) is a biomarker of oxidative stress which is essentially involved in the pathophysiology of many diseases. The analysis of HNE is challenging because this aldehyde is extremely reactive and thus unstable. Hence, we adopted a gas chromatography–mass spectrometry (GC–MS) method based on derivatization of HNE with pentafluorobenzylhydroxylamine–HCl followed by trimethylsilylation to trimethylsilyl ethers. Ions representative for a negative ion chemical ionization mode were recorded at m/z = 152 for HNE and at m/z = 162 for the deuterated analogon (HNE-d11) as internal standard. This excellent stable and precise GC–MS method was carefully validated for HNE, and showed good linearity (r2 = 0.998), and high specificity and sensitivity. Within-day precisions were 4.4–6.1% and between-day precisions were 5.2–10.2%. Accuracies were between 99% and 104% for the whole calibration range (2.5–250 nmol/L) of HNE.To examine the versatility of this modified GC–MS method, we analyzed HNE in ethylenediaminetetraacetic acid (EDTA) plasma in a well-defined collective of migraine patients; recently published. The results underline our former observations that women with migraine are afflicted with increased levels of HNE. Patients with thyroidal dysfunction showed no significant HNE alterations. This was confirmed by normal HNE EDTA plasma levels in hyper- und hypothyroid Sprague-Dawley rats.Taken together, the GC–MS method presented herein is of excellent quality to record oxidative stress-related bioactive HNE levels. This is important for a reorientation of oxidative stress analytics in other human diseases first of atherosclerosis and cancer. 相似文献
68.
《Free radical research》2013,47(5):572-579
AbstractPurpose. Ionizing radiation generates free radicals and reactive oxygen species that induce DNA damage in vivo. This study aimed to determine the relationship between serum reactive oxygen metabolite (ROM) levels and skin reaction after irradiation in a rat model. Methods and materials. I. Female Wistar rats were classified into 0 Gy (control), 2 Gy, and 30 Gy groups; serum ROM levels were measured in the very acute phase. II. Other female Wistar rats were classified into 0 Gy (control), 30 Gy, 50 Gy, and 70 Gy groups; serum ROM levels were measured before and 3, 7, 16, 24, 31, and 38 days after irradiation. Skin reaction was evaluated according to the SRS (0–5) twice every week. Results. Serum ROM levels in the subacute phase were significantly higher in the 50 and 70 Gy groups than in the 0 and 30 Gy groups [p = 0.029, repeated-measure analysis of variance (ANOVA)]. As expected, SRSs increased in the order of the 0 Gy, 30 Gy, 50 Gy, and 70 Gy groups and differed significantly among these groups (p < 0.001, repeated-measure ANOVA). Peak serum ROM levels were observed 16 days after irradiation in all irradiated groups and corresponded with the appearance of visible skin reaction after irradiation. Conclusions. Serum ROM levels may be useful for evaluating radiation damage in mammals. Further investigations are required to investigate changes in intracellular metabolism after irradiation at gene and protein levels. 相似文献
69.
Zheyong Huang Yunli Shen Hongmin Zhu Jianfeng Xu Yanan Song Xinying Hu Zhang Shuning Xiangdong Yang Aijun Sun Juying Qian Junbo Ge 《Experimental Animals》2013,62(3):197-203
Cell delivery via the retrograde coronary route boasts less vessel embolism, myocardial
injury, and arrhythmogenicity when compared with those via antegrade coronary
administration or myocardial injection. However, conventional insertion into the coronary
sinus and consequent bleeding complication prevent its application in small animals. To
overcome the complication of bleeding, we described a modified coronary retroinfusion
technique via the jugular vein route in rats with myocardial infarction (MI). A flexible
wire with a bent end was inserted into the left internal jugular vein and advanced slowly
along the left superior vena cava. Under direct vision, the wire was run into the left
cardiac vein by rotating the wire and changing the position of its tip. A fine tube was
then advanced along the wire to the left cardiac vein. This modified technique showed less
lethal hemorrhage than the conventional technique. Retroinfusion via transjugular catheter
enabled efficient fluid or cell dissemination to the majority areas of the free wall of
the left ventricle, covering the infarcted anterior wall. In conclusion, transjugular
cardiac vein catheterization may make retrocoronary infusion a more safe and practical
route for delivering cell, drug, and gene therapy into the infarcted myocardium of
rats. 相似文献
70.
The measurement of glomerular filtration rate (GFR) is the gold standard in kidney function assessment. Currently, investigators determine GFR by measuring the level of the endogenous biomarker creatinine or exogenously applied radioactive labeled inulin (3H or 14C). Creatinine has the substantial drawback that proximal tubular secretion accounts for ~50% of total renal creatinine excretion and therefore creatinine is not a reliable GFR marker. Depending on the experiment performed, inulin clearance can be determined by an intravenous single bolus injection or continuous infusion (intravenous or osmotic minipump). Both approaches require the collection of plasma or plasma and urine, respectively. Other drawbacks of radioactive labeled inulin include usage of isotopes, time consuming surgical preparation of the animals, and the requirement of a terminal experiment. Here we describe a method which uses a single bolus injection of fluorescein isothiocyanate-(FITC) labeled inulin and the measurement of its fluorescence in 1-2 μl of diluted plasma. By applying a two-compartment model, with 8 blood collections per mouse, it is possible to measure GFR in up to 24 mice per day using a special work-flow protocol. This method only requires brief isoflurane anesthesia with all the blood samples being collected in a non-restrained and awake mouse. Another advantage is that it is possible to follow mice over a period of several months and treatments (i.e. doing paired experiments with dietary changes or drug applications). We hope that this technique of measuring GFR is useful to other investigators studying mouse kidney function and will replace less accurate methods of estimating kidney function, such as plasma creatinine and blood urea nitrogen. 相似文献