全文获取类型
收费全文 | 5324篇 |
免费 | 178篇 |
国内免费 | 1篇 |
专业分类
5503篇 |
出版年
2023年 | 4篇 |
2022年 | 2篇 |
2021年 | 14篇 |
2020年 | 8篇 |
2019年 | 9篇 |
2018年 | 23篇 |
2017年 | 20篇 |
2016年 | 38篇 |
2015年 | 42篇 |
2014年 | 48篇 |
2013年 | 54篇 |
2012年 | 432篇 |
2011年 | 534篇 |
2010年 | 101篇 |
2009年 | 84篇 |
2008年 | 517篇 |
2007年 | 520篇 |
2006年 | 506篇 |
2005年 | 450篇 |
2004年 | 422篇 |
2003年 | 410篇 |
2002年 | 360篇 |
2001年 | 254篇 |
2000年 | 303篇 |
1999年 | 160篇 |
1998年 | 28篇 |
1997年 | 14篇 |
1996年 | 9篇 |
1995年 | 9篇 |
1994年 | 9篇 |
1993年 | 11篇 |
1992年 | 10篇 |
1991年 | 9篇 |
1990年 | 6篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1980年 | 2篇 |
1978年 | 4篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 5篇 |
1971年 | 7篇 |
1970年 | 9篇 |
1969年 | 5篇 |
1968年 | 8篇 |
排序方式: 共有5503条查询结果,搜索用时 15 毫秒
91.
Ziegelhöffer A Styk J Ravingerová T Seboková J Volkovová K Waczulíková I Cársky J Dzurba A Docolomanský P 《Life sciences》1999,65(18-19):1999-2001
Recently it was shown that besides their negative role in pathogenesis of diabetes, reactive oxygen species (ROS) and particularly the products of non-enzymatic glycation of proteins (NEGP) may also participate in some processes of adaptation of the myocardium to diabetes, such as in the mechanism of development of calcium resistance of the heart. Our study revealed that the hearts of rats with experimentally induced diabetes (single dose of streptozotocin, 45 mg/kg i.v., 6 U/kg insulin daily) develop considerable resistance against calcium overload (induced by means of Ca-paradox). On the day 63 after the beginning of experiment, when the diabetic cardiomyopathy became fully developed but the hearts were still not failing, their calcium resistance was increased to 83.33%. Our results provide evidence that, when applied in a special regimen, resorcylidene aminoguanidine (RAG, 4 mg/kg) prevented both, the formation of fructosamine (a source of ROS generation), and also that of the advanced Maillard products, in the heart sarcolemma of diabetic rats. The effect of RAG was accompanied by a decrease in calcium resistance in the group of rats with chronic diabetes (63 days) from 83.3 to 46.7%. It is concluded that NEGP and ROS formation are inevitably needed for development of calcium resistance in the diabetic hearts. 相似文献
92.
Pospísil M Hofer M Netíková J Holá J Znojil V Vácha J Vacek A 《Radiation research》1999,151(3):363-367
The purpose of this study was to investigate effects of the treatment prior to irradiation with granulocyte colony-stimulating factor (G-CSF) on hematopoiesis in B10CBAF1 mice exposed to a sublethal dose of 6.5 Gy of 60Co gamma radiation. G-CSF was administered in a 4-day regimen (3 microg/day); irradiation followed 3 h after the last injection of G-CSF. Such a treatment was found to stimulate granulopoiesis, as shown by increased counts of granulocyte-macrophage progenitor cells (GM-CFC) and of granulocytic cells in the femoral marrow and spleen at the time of irradiation. However, postirradiation counts of GM-CFC and granulocytic cells in the marrow of mice pretreated with G-CSF were reduced up to day 18 after irradiation. Interestingly, the D0 values for marrow GM-CFC determined 1 h after in vivo irradiation were 1.98 Gy for controls and 2.47 Gy for mice pretreated with G-CSF, indicating a decreased radiosensitivity of these cells after drug treatment. The inhibitory effects of the pretreatment with G-CSF on the postirradiation granulopoiesis could be attributed to the phenomenon of "rebound quiescence" which can occur after cessation of the treatment with growth factors. Postirradiation recovery of erythropoiesis in the spleen of mice pretreated with G-CSF exhibited a dramatic increase and compensated for the decreased erythropoiesis in the marrow at the time of irradiation. This complexity of the hematopoietic response should be taken into account when administering G-CSF in preirradiation regimens. 相似文献
93.
Bec N Anzenbacher P Anzenbacherová E Gorren AC Munro AW Lange R 《Biochemical and biophysical research communications》1999,266(1):187-189
Here we describe for the first time the formation of a complex of reduced CYP102 (cytochrome P450 BM-3) heme domain with molecular oxygen. To stabilize the oxycomplex, the experiments had to be done under argon atmosphere at cryogenic temperatures (-25 degrees C) in the presence of 50% glycerol. The spectral properties of this species were different from those of another P450-type autosuffisant enzyme, i.e., the neuronal nitric oxide synthase. On the contrary, the oxyferrous complex of CYP102 possesses spectral properties similar to those of complexes of microsomal cytochromes P450, e.g., CYP2B4. 相似文献
94.
Species of amoebae belonging to the genera Platyamoeba Page, 1969, Vannella Bovee, 1965 and Flabellula Schaeffer, 1926 were found to accompany Paramoeba sp., the agent of amoebic gill disease (AGD), in clinically diseased turbots. The same community of epizoic gymnamoebae was found on the gills of turbots which revealed no gill abnormalities but slight behavioral signs indicative of suboptimal health status. The assemblage of the above-mentioned free-living amoebae capable of colonizing gill tissue of turbots was supplemented with species recognized in samples fixed from primary isolates for transmission electron microscopy. The pathogenic potential of epizoic gill amoebae in turbots is discussed. 相似文献
95.
Based on a fine structural study, a new genus, Kabataia gen. n., is proposed for Microsporidium arthuri Lom, Dyková and Shaharom, 1990. It develops in trunk muscles of a South-East Asian freshwater fish, Pangasius sutchi. The genus has nuclei isolated throughout the cycle, merogony stages are multinucleate, sporogony proceeds in 2 steps: multinucleate sporont segments into sporoblast mother cells which produce 2 sporoblasts. Sporoblasts and early spores are characterized by a dense globule at the site of the posterior vacuole. Mature spores are of a rather variable shape. Their exospore is raised into small, irregular fields. The polaroplast is relatively small and its posterior part consists of flat vesicles with dense contents. The polar tube makes a small number (4 to 6) of turns. A congeneric species is Kabataia seriolae (Egusa, 1982) comb. nov. from cultured marine yellowtails Seriola quinqueradiata. Kabataia inflicts heavy damage on muscle tissue. The sarcoplasm within which Kabataia develops is reduced to an amorphous mass with tubule-like fibrils, microfibrils and small vesicles. 相似文献
96.
Previous investigations have demonstrated that increased ovarian function during pseudopregnancy in the rat may be associated with alterations of the physical state of membranes. Changes in rigidity of membrane lipids were observed during the formation as well as regression of corpora lutea. The effects of cyclooxygenase inhibitors (indomethacin and acetylsalicylic acid (ASA)) and of selected steroids (estradiol, testosterone and dihydrotestosterone) on the functional state of luteinized ovaries were studied. The compounds were administered to the animals in silastic capsules on different days after hCG injection. ASA and indomethacin administration on days 10 and 11 after hCG injection resulted in an increase in the LH/hCG receptor binding activity and rigidity of ovarian membrane lipids, as determined by fluorescence polarization of 1,6-diphenyl-1,3,5 hexatriene (DPH) probe. This effect was apparent within 7 days after indomethacin and ASA treatment. Both estradiol and testosterone significantly increased the ovarian LH/hCG binding activity, however estradiol did not affect the membrane lipid rigidity. Unlike testosterone, the administration of dihydrotestosterone induced a decrease in membrane lipid rigidity and reduced the accessibility of the LH/hCG receptor. Inhibitors of prostaglandin F2alpha (PGF2alpha) synthesis, as the endogenous mediator of luteolysis, were shown to delay the regression of the corpora lutea and to prolong the luteal activity in pseudopregnant rats. 相似文献
97.
Arthritis adjuvans was studied in the murine model. An effect of different treatment (methotrexate, tauredon, collagen hydrolysate) was estimated in the course of developing disease (day 3, 5, 11 and 21). Repeated evaluation of body weight and peripheral blood leukograms as a total response of organism was performed. Oedema of paw periarticular and tail regions, light- and electron-microscopical screening and immunohistochemical investigation of prevalence of interleukin-1-beta (IL-1beta) and tumour necrosis factor (TNF-alpha) were estimated. The most pronounced benefit effect of methotrexate at stabilization of the monocytes blood level, synovial membrane cell invasion and TNF-alpha immunopositivity was ascertained. 相似文献
98.
The aim of this study was to investigate, if transient spinal ischemia and a period of 4-day reperfusion will change the distribution pattern of substance P in the spinal cord of rabbits. Strongly enhanced staining of substance P positive nerve structures appeared in the superficial dorsal horn (laminae I, II), the Lissauer's tract, the pericentral region (lamina X), and in the areas of autonomic nuclei (sympathetic-intermediolateral--IML nucleus and parasympathetic-sacral parasympathetic nucleus--SPN) in the control group. Transient spinal ischemia was produced by occlusion of the abdominal aorta just below the left renal artery. Neuropathology of the lesion 4 days after transient ischemia was characterized by selective necrosis of gray matter in the central part of dorsal horn and medial portions of anterior gray matter. Areas with the most dense accumulation of substance P positive structures stayed almost intact. Therefore, no significant change in the distribution pattern of substance P was found in the spinal cord of animals with ischemia-reperfusion-induced injury. 相似文献
99.
The distribution of Pan cytokeratin and cytokeratin 18 in the dog and sheep urinary bladder and ureter as seen by immunohistochemistry using monoclonal antibodies is described. Both cytokeratins were observed in the urinary bladder and ureter of the studied species. Differences in their localization are described. 相似文献
100.
Cernochová D Pospísilová E Nepozitková D Havelka P Lichnovský V 《General physiology and biophysics》1999,18(Z1):90-93
We have studied expression of PCNA and Ki-67 in the developing nervous system, sensory organs and orofacial regions in human embryos and fetuses, using monoclonal antibodies PC-10 and MIB-1 in three-step immunohistochemical method and apoptosis performed by TUNEL technique. Expression of PCNA and Ki-67 increased with the age. Apoptosis was rare in above mentioned regions. 相似文献