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   3878篇
  免费   484篇
  国内免费   3篇
  2023年   16篇
  2021年   102篇
  2020年   68篇
  2019年   67篇
  2018年   106篇
  2017年   70篇
  2016年   130篇
  2015年   216篇
  2014年   218篇
  2013年   234篇
  2012年   249篇
  2011年   252篇
  2010年   175篇
  2009年   136篇
  2008年   161篇
  2007年   230篇
  2006年   180篇
  2005年   151篇
  2004年   133篇
  2003年   128篇
  2002年   137篇
  2001年   111篇
  2000年   90篇
  1999年   84篇
  1998年   44篇
  1997年   45篇
  1996年   33篇
  1995年   34篇
  1994年   38篇
  1993年   26篇
  1992年   69篇
  1991年   57篇
  1990年   52篇
  1989年   64篇
  1988年   28篇
  1987年   38篇
  1986年   30篇
  1985年   42篇
  1984年   45篇
  1983年   29篇
  1982年   27篇
  1981年   20篇
  1980年   13篇
  1979年   16篇
  1978年   22篇
  1977年   18篇
  1975年   18篇
  1974年   12篇
  1973年   17篇
  1970年   14篇
排序方式: 共有4365条查询结果,搜索用时 15 毫秒
121.
122.
In a study of Malaysians of different racial groups, 1,510 sera (908 from Malays, 371 from Chinese and 231 from Indians) were identified for their protease inhibitor (Pi) types. The gene frequencies for the alleles PiM, PiS and PiX in Malays were, respectively, 0.979, 0.015, and 0.007. In Chinese, the frequencies were 0.981, 0.019 and 0.000, and in Indians they were 0.976, 0.24, and 0.000. It is interesting that the usually rare PiX type is found in appreciable frequency in the Malays. Two different types with unusual behavior and obscure origin were also found.  相似文献   
123.
Summary A dysmorphic female born with partial trisomy of the proximal segment of the long arm of chromosome 14 had 47 chromosomes. The extra one was acrocentric, smaller than the D group, and bigger than the G-chromosome group. By GTG banding it was identified as a deleted chromosome 14, the karyotype being 47,XX,+del 14(q24). Chromosome analysis of the parents was normal.  相似文献   
124.
Candida lipolytica was grown continuously on n-hexadecane as the main source of carbon. A transient continuous-culture experiment was also conducted to investigate hydrocarbon-limited growth; the hydrocarbon feed flow rate was stopped for several hours and then resumed at a reduced steady-state flow rate. Interfacial tension, Sauter mean diameter, pseudosolubility, fraction of cells in the aqueous phase, oil-phase volume fraction, and cell concentration were measured to characterize the system. The microorganisms appear to utilize both the submicron drops and the microscopic drops. The effects of interfacial tension, pseudosolubility, and unoccupied interfacial area on the kinetics of hydrocarbon fermentation are discussed here. A conceptual model for hydrocarbon uptake is presented and discussed.  相似文献   
125.
M Finke  V Sachs  B Vollert  M Lopez  C Salmon  H H Hoppe  K Fischer 《Blut》1976,32(5):371-374
The serum of a patient (Mr. Lat) with the regular blood group A1 B contains an anti-B reacting with all cells having a B antigen except Bx and cis AB. The anti-B reacts at 4 degrees C and occasionally at room temperature as shown by agglutination, absorption-eluction and by thermo-dynamic assays. The antibody is regarded as an irregular autoantibody belonging to the group of the so called "suppressed" or "latent" antibodies.  相似文献   
126.
Summary The orderly organization in a number of discrete classes of weight persists in the hepatocytes during acute and chronic poisoning with thioacetamide and during a prolonged treatment with hydrocortisone, though many striking cytological and structural changes occur in the liver.The number of hepatocyte classes decreases under hydrocortisone treatment and during acute and chronic thioacetamide poisoning, and increases during recovery after acute thioacetamide poisoning and during the late phases of chronic thioacetamide poisoning. This is due to decrements and increments in dry mass of the hepatocytes, which occur by steps, through repeated losses and additions of a constant amount of solids substantially corresponding to the class period.Such a mechanism is similar to that acting in the hepatocyte atrophy due to starvation and in the hepatocyte enlargement occurring during postnatal development. Therefore, the increment and the decrement in dry mass by defined steps takes place in the hepatocytes in both physiological and pathological conditions.This work was supported by a grant of the Consiglio Nazionale delle Ricerche, Rome, Italy.  相似文献   
127.
The uptake of methyl α-d-glucopyranoside (α-MG) by Escherichia coli K12 was decreased by the addition of substrates which stimulated the rate of oxygen consumption by the cells. The inhibition, which occurred only at non-saturating concentrations of α-MG, was not the result of a stimulation of the rate of exit of intracellular α-MG, and was abolished by the presence of carbonyl cyanide m-chlorophenylhydrazone or sodium azide. Since those drugs inhibit energy conservation at the respiratory chain and did not alter significantly the rate of oxygen consumption under the conditions for the assay of α-MG uptake, it appears that the inhibition of the transport system by respirable substrates is mediated by some form of energy derived from respiration.  相似文献   
128.
129.
130.
Lopez  Renee A.  Renzaglia  Karen S. 《Planta》2016,243(4):947-957
Planta - Both male and female gametes of archegoniates are highly specialized cells surrounded by an extraprotoplasmic matrix rich in AGPs, which are speculated to facilitate development and gamete...  相似文献   
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