全文获取类型
收费全文 | 454篇 |
免费 | 34篇 |
国内免费 | 2篇 |
专业分类
490篇 |
出版年
2023年 | 4篇 |
2022年 | 6篇 |
2021年 | 15篇 |
2020年 | 11篇 |
2019年 | 7篇 |
2018年 | 9篇 |
2017年 | 15篇 |
2016年 | 16篇 |
2015年 | 32篇 |
2014年 | 13篇 |
2013年 | 32篇 |
2012年 | 47篇 |
2011年 | 23篇 |
2010年 | 20篇 |
2009年 | 17篇 |
2008年 | 22篇 |
2007年 | 20篇 |
2006年 | 24篇 |
2005年 | 21篇 |
2004年 | 13篇 |
2003年 | 17篇 |
2002年 | 16篇 |
2001年 | 10篇 |
2000年 | 4篇 |
1999年 | 8篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1982年 | 4篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1973年 | 1篇 |
1968年 | 1篇 |
1967年 | 2篇 |
1966年 | 1篇 |
1965年 | 2篇 |
1964年 | 2篇 |
1937年 | 1篇 |
排序方式: 共有490条查询结果,搜索用时 0 毫秒
11.
Preet A Gupta BL Siddiqui MR Yadava PK Baquer NZ 《Molecular and cellular biochemistry》2005,278(1-2):21-31
Vanadium has been reported to have broad pharmacological activity both in vitro and in vivo. Vanadium compound, sodium orthovanadate, Na3VO4, is well known for its hypoglycaemic effects. However, Na3VO4 exerts these effects at relatively high doses (0.6 mg/ml) and exhibit several toxic effects. In the present study lower doses
of Na3VO4 (0.2 mg/ml) are combined with Trigonella foenum graecum seed powder (TSP), another hypoglycaemic agent, to reduce its toxicity without compromising its antidiabetic potential. The
efficacy of the lower doses of Na3VO4 has been investigated in restoring the altered glucose metabolism and histological structure in the sciatic nerves in 21
and 60 days alloxan diabetic rats. A portion of the glucose was found to be channelled from the normal glycolytic route to
polyol pathway, evident by the reduced hexokinase activity and increased polyol pathway enzymes aldose reductase and sorbitol
dehydrogenase activity causing accumulation of sorbitol and fructose in diabetic conditions. Ultrastructural observation of
the sciatic nerve showed extensive demylination and axonal loss after eight weeks of diabetes induction. Blood glucose levels
increased in diabetic rats were normalized with the lower dose of vanadium and Trigonella treatment. The treatment of the diabetic rats with vanadium and Trigonella prevented the activation of the polyol pathway and sugar accumulations. The sciatic nerves were also protected against the
structural abnormalities found in diabetes with Trigonella foenum graecum as well as Na3VO4. Results suggest that lower doses of Na3VO4 may be used in combination with TSP as an efficient antidiabetic agent to effectively control the long-term complications
of diabetes in tissues like peripheral nerve. 相似文献
12.
To elucidate the cause of prenatal and early postnatal death in giant panda, pathological studies have been carried out on paraffin-fixed tissue sections from two fetuses and four cubs. The fetuses appeared to have classical atrophic changes in lung and hemorrhage in multiple organs, whereas the cubs showed purulent inflmnmation in various organs, most profound in lung and umbilicus. Localized infusion of bacteria and neutrophils were identified in the focus. Acute enteritis and hepatitis were also observed, as well as purulent encephalitis in one case. Variable degrees of congestion, hemorrhage, denaturalization and putrescence were evident in heart, liver, spleen, kidney, intestines, and lymph nodes. The results indicated that the fetuses died from suffocation whereas the cubs died from infection. 相似文献
13.
Jennifer N. Murdoch Christine Damrau Anju Paudyal Debora Bogani Sara Wells Nicholas D. E. Greene Philip Stanier Andrew J. Copp 《Disease models & mechanisms》2014,7(10):1153-1163
Neural tube defects (NTDs) are among the commonest and most severe forms of developmental defect, characterized by disruption of the early embryonic events of central nervous system formation. NTDs have long been known to exhibit a strong genetic dependence, yet the identity of the genetic determinants remains largely undiscovered. Initiation of neural tube closure is disrupted in mice homozygous for mutations in planar cell polarity (PCP) pathway genes, providing a strong link between NTDs and PCP signaling. Recently, missense gene variants have been identified in PCP genes in humans with NTDs, although the range of phenotypes is greater than in the mouse mutants. In addition, the sequence variants detected in affected humans are heterozygous, and can often be detected in unaffected individuals. It has been suggested that interactions between multiple heterozygous gene mutations cause the NTDs in humans. To determine the phenotypes produced in double heterozygotes, we bred mice with all three pairwise combinations of Vangl2Lp, ScribCrc and Celsr1Crsh mutations, the most intensively studied PCP mutants. The majority of double-mutant embryos had open NTDs, with the range of phenotypes including anencephaly and spina bifida, therefore reflecting the defects observed in humans. Strikingly, even on a uniform genetic background, variability in the penetrance and severity of the mutant phenotypes was observed between the different double-heterozygote combinations. Phenotypically, Celsr1Crsh;Vangl2Lp;ScribCrc triply heterozygous mutants were no more severe than doubly heterozygous or singly homozygous mutants. We propose that some of the variation between double-mutant phenotypes could be attributed to the nature of the protein disruption in each allele: whereas ScribCrc is a null mutant and produces no Scrib protein, Celsr1Crsh and Vangl2Lp homozygotes both express mutant proteins, consistent with dominant effects. The variable outcomes of these genetic interactions are of direct relevance to human patients and emphasize the importance of performing comprehensive genetic screens in humans.KEY WORDS: Neural tube defects, Planar cell polarity, Genetic interactions, Craniorachischisis, Multiple heterozygosity 相似文献
14.
Sequence variation and genetic diversity in the giant panda 总被引:3,自引:0,他引:3
ZHANG YapingOliver A. RyderFAN Zhiyong ZHANG HemingHE TingmeiHE Guangxin ZHANG Anju FEI LisongZHONG Shunlong CHEN HongZHANG Chenglin YANG Minghai ZHU Feibing PENG Zhenxin PU Tianchun CHEN Yucun YAO OMinda GUO Wei 《中国科学:生命科学英文版》1997,40(2):210-216
About 336–444 bp mitochondrial D-loop region and tRNA gene were sequenced for 40 individuals of the giant panda which were
collected from Mabian, Meigu, Yuexi, Baoxing, Pingwu, Qingchuan, Nanping and Baishuijiang, respectively. 9 haplotypes were
found in 21 founders. The results showed that the giant panda has low genetic variations, and that there is no notable genetic
isolation among geographical populations. The ancestor of the living giant panda population perhaps appeared in the late Pleistocene,
and unfortunately, might have suffered bottleneck attacks. Afterwards, its genetic diversity seemed to recover to some extent.
Project supported by the “8.5” Key Project of Chinese Academy of Sciences, the Chairman Foundation of Chinese Academy of Sciences,
K. C. Wang Education Foundation, the Applied Basic Research Foundation of Yunnan, the National Natural Science Foundation
of China, the Special Foundation for Returned Chinese Scientists, and Zoological Society of San Diego. 相似文献
15.
Kumar D Bansal A Thomas P Sairam M Sharma SK Mongia SS Singh R Selvamurthy W 《International journal of biometeorology》1999,42(4):201-204
High altitude stress leads to lipid peroxidation and free radical formation which results in cell membrane damage in organs
and tissues, and associated mountain diseases. This paper discusses the changes in biochemical parameters and antibody response
on feeding glutamate to male albino Sprague Dawley rats under hypoxic stress. Exposure of rats to simulated hypoxia at 7576
m, for 6 h daily for 5 consecutive days, in an animal decompression chamber at 32±2° C resulted in an increase in plasma malondialdehyde
level with a concomitant decrease in blood glutathione (reduced) level. Supplementation of glutamate orally at an optimal
dose (27 mg/kg body weight) in male albino rats under hypoxia enhanced glutathione level and decreased malondialdehyde concentration
significantly. Glutamate feeding improved total plasma protein and glucose levels under hypoxia. The activities of serum glutamate
oxaloacetate transaminase (SGOT) and serum glutamate pyruvate transaminase (SGPT) and the urea level remained elevated on
glutamate supplementation under hypoxia. Glutamate supplementation increased the humoral response against sheep red blood
cells (antibody titre). These results indicate a possible utility of glutamate in the amelioration of hypoxia-induced oxidative
stress.
Received: 23 March 1998 / Accepted: 19 October 1998 相似文献
16.
Potato chips industry wastewater was collected and analyzed for biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS) and total carbohydrates. Two Aspergillus species, A. foetidus and A. niger, were evaluated for their ability to grow and produce biomass and reduce the organic load of the wastewater. A. foetidus MTCC 508 and A. niger ITCC 2012 were able to reduce COD by about 60% and produce biomass 2.4 and 2.85 gl(-1), respectively. Co-inoculation of both Aspergillus strains resulted in increased fungal biomass production and higher COD reduction than in individual culture at different culture pH. pH 6 was optimum for biomass production and COD reduction. Amendment of the wastewater with different N and P sources, increased the biomass production and COD reduction substantially. Under standardized conditions of pH 6 and amendment of wastewater with 0.1% KH2PO4 and 0.1% (NH4)2 SO4, a mixed culture gave 90% reduction in COD within 60 h of incubation. 相似文献
17.
18.
19.
Amoebocyte is the single type of cell circulating in the horseshoe crab hemolymph, which plays a major role in the defense system of the animal. Granules present in these cells are sensitive to nanogram quantities of bacterial endotoxins, which form the basis of the Limulus amoebocyte lysate (LAL) test. Normally, amoebocytes for the production of the LAL are collected by cardiac puncture; hence, development of the in vitro culture system for amoebocytes will reduce the variability of the lysate and help to conserve the 400 million-yr-old living fossil. In the present investigation we have attempted organ culture of gill flaps that have been shown to be the source of amoebocytes. The gill flaps were cultured at 28 degrees C on a rocker platform in a modified L-15 medium supplemented with 10% v/v horseshoe crab serum. This led to the release of amoebocytes outside the gill flaps for a period of 6-8 wk with a more or less steady number of amoebocytes during the weekly harvest. No significant difference was seen in the yield of amoebocytes from male and female horseshoe crabs. Confocal laser microscopy studies revealed significant difference in the size of amoebocytes released in vitro as compared with those obtained in vivo. Thus, we have optimized the culture conditions for the long-term generation of amoebocytes in vitro from the Indian horseshoe crab Tachypleus gigas by reducing the incidence of contamination, simulating in vivo conditions for the organ culture of gill flaps, and improvising the nutritional status using the modified L-15 medium, providing the desired osmolarity and pH. 相似文献
20.
Chintamani Sharma R Badran R Singhal V Saxena S Bansal A 《World journal of surgical oncology》2003,1(1):13