首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   8477篇
  免费   495篇
  国内免费   2篇
  2022年   44篇
  2021年   113篇
  2020年   74篇
  2019年   76篇
  2018年   117篇
  2017年   106篇
  2016年   153篇
  2015年   258篇
  2014年   326篇
  2013年   544篇
  2012年   466篇
  2011年   487篇
  2010年   269篇
  2009年   281篇
  2008年   432篇
  2007年   439篇
  2006年   415篇
  2005年   413篇
  2004年   450篇
  2003年   380篇
  2002年   374篇
  2001年   248篇
  2000年   244篇
  1999年   206篇
  1998年   98篇
  1997年   88篇
  1996年   72篇
  1995年   84篇
  1994年   91篇
  1993年   85篇
  1992年   150篇
  1991年   125篇
  1990年   119篇
  1989年   139篇
  1988年   101篇
  1987年   108篇
  1986年   86篇
  1985年   81篇
  1984年   70篇
  1983年   62篇
  1982年   43篇
  1981年   44篇
  1980年   31篇
  1979年   59篇
  1978年   30篇
  1977年   42篇
  1976年   23篇
  1975年   25篇
  1974年   29篇
  1973年   25篇
排序方式: 共有8974条查询结果,搜索用时 15 毫秒
81.
The in vivo effect of an analog of LH-RH, (Des-Gly-NH210, Proethylamide9)-LH-RH, on LH release, was studied in one bull with azooapermia, and one cow with cystic follicle. The single intravenous injection of 100 μg LH-RH analog caused abrupt and marked increase in serum LH and the high levels of LH were maintained for 3 hours. The highest levels of serum LH were 48 and 114 times as high as the pre-treatment levels in a bull and a cow, respectively. Further studies are being undertaken to evaluate this compound for improving reproductive function in cattle.  相似文献   
82.
Various methods were tried for the immobilization of aspartase, and the preparation having the highest activity was obtained when partially purified aspartase from Escherichia coli was entrapped into polyacrylamide gel Iattice. Enzymatic properties of the immobilized aspartase were investigated and compared with those of the native aspartase. With regard to optimum pH, temperature, concentration of Mn++, kinetic constants and heat stability, no marked difference was observed between the native and immobilized aspartases. By employing an enzyme column packed with the immobilized aspartase, conditions for continuous production of L -aspartic acid from ammonium fumarate were investigated. When a solution of 1M ammonium fumarate (pH 8.5, containing 1mM MnCl2) was passed through the aspartase column at the flow rate of SV = 0.08 at 37°C, the highest rate of reaction was attained. From the column effluents, L-aspartic acid was obtained in a good yield.  相似文献   
83.
84.
85.
86.
Summary Histochemical study in epiphyseal cartilages and periodontal tissues of the rat subjected to cortisone and PTH administration was examined enzyme histochemically in the decalcified frozen sections with neutral EDTA.In cortisone and PTH-treated rats, altered proliferating cartilage cells in the epiphysis revealed a weak, and decreasing activities of oxidative enzymes with the comparison to those of the control, however, they showed similar activity for alkaline and acid phosphatases as normal cells.Epiphysis and alveolar bones in large dose of cortisone administered rats exhibited an absence or markedly decreasing number of osteoclasts, but on the contrary, those of PTH treated rats led to an increased number of the cells. Osteoclasts in hormone treated conditions were characterized by the existence of the strong succinate dehydrogenase activity as well as in normal status.  相似文献   
87.
Summary Zymogramic analysis of esterase in the mouse, rat and guinea-pig salivary glands was undertaken and demonstrated species and organ specificities of esterase with electrophoretic method. Salivary glands esterase was classified into A, B and C types based on the electrophoretic mobility. Mouse submandibular gland had the most complicated pattern, while guinea-pig showed the simpliest patterns which was devoid of B type of esterase. Rat salivary glands exhibited rather regular patterns. Similar zymogram patterns were obtained with many kinds of ester compounds, that is simple and substituted naphthol esters and indoxyl derivatives. The tests of inhibition and activation for esterase activity was obtained. Histochemical properties applied to inhibitor test in the esterase zymogram patterns showed no marked differences between ducts and acini.  相似文献   
88.
89.
Summary Analysis of lactate and malate dehydrogenase zymograms of rodent salivary glands showed species and organ specific patterns.Lactate dehydrogenase isoenzyme patterns occupied the middle positions in relation to those of skeletal and heart muscle. Activities of the major salivary glands were in the order submaxillary gland>parotid>sublingual gland. Zymogram of the mouse and rat showed LDH4 and LDH5 high activity patterns, while that of the rabbit was the fast moving active one. Hamster salivary gland exhibited a neutral type of the former and the latter.Malate dehydrogenase isoenzyme exhibited very similar patterns for the mouse, rat and hamster. Malate dehydrogenase zymogram of rabbit showed 3 active bands, which was different from the other rodents.  相似文献   
90.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号