全文获取类型
收费全文 | 6619篇 |
免费 | 650篇 |
国内免费 | 3篇 |
专业分类
7272篇 |
出版年
2022年 | 44篇 |
2021年 | 74篇 |
2020年 | 53篇 |
2019年 | 78篇 |
2018年 | 92篇 |
2017年 | 76篇 |
2016年 | 131篇 |
2015年 | 239篇 |
2014年 | 264篇 |
2013年 | 324篇 |
2012年 | 471篇 |
2011年 | 486篇 |
2010年 | 297篇 |
2009年 | 253篇 |
2008年 | 386篇 |
2007年 | 388篇 |
2006年 | 324篇 |
2005年 | 341篇 |
2004年 | 312篇 |
2003年 | 311篇 |
2002年 | 292篇 |
2001年 | 123篇 |
2000年 | 108篇 |
1999年 | 114篇 |
1998年 | 71篇 |
1997年 | 67篇 |
1996年 | 51篇 |
1995年 | 59篇 |
1994年 | 57篇 |
1993年 | 48篇 |
1992年 | 71篇 |
1991年 | 74篇 |
1990年 | 61篇 |
1989年 | 63篇 |
1988年 | 73篇 |
1987年 | 58篇 |
1986年 | 59篇 |
1985年 | 58篇 |
1984年 | 51篇 |
1983年 | 56篇 |
1982年 | 45篇 |
1981年 | 37篇 |
1980年 | 34篇 |
1979年 | 48篇 |
1978年 | 35篇 |
1977年 | 41篇 |
1976年 | 31篇 |
1973年 | 38篇 |
1972年 | 29篇 |
1971年 | 34篇 |
排序方式: 共有7272条查询结果,搜索用时 15 毫秒
1.
Yohannes M. S. Samosir Steve Adkins 《In vitro cellular & developmental biology. Plant》2014,50(4):493-501
An in vitro photoautotrophic step based on the supply of CO2-enriched air (1,600 μmol mol?1) during the light phase and ambient air (350 μmol mol?1 CO2) during the dark phase has been used to promote the ex vitro establishment of coconut (Cocos nucifera L.) seedlings. The introduction of this step into a previously developed in vitro protocol was found to improve the quality of the seedlings (as assessed by fresh weight increase, physical stature, leaf area and thickness, stomatal density, and chlorophyll a content, and primary and secondary root production), the proportion of seedlings successfully transferred to soil (improvement from 40% to 100%) and achieved in a shorter time (reduction from 10 to 6 mo). Best results using this photoautotrophic growth step were obtained when a low medium concentration of sucrose (43.8 mM or lower) was used, when it was applied to seedlings that had already reached 4 or 5 mo of age in the in vitro culture step, and when seedlings were cultured in the photoautotrophic system for 2 mo or more before transfer to soil. Our improved protocol is more efficient and it reduces the cost per plant for the international exchange of coconut germplasm. 相似文献
2.
3.
The congenitally jaundiced Gunn rat does not conjugate bilirubin but does conjugate bilirubin dimethyl diester. Partial defects in conjugating p-nitrophenol and demethylating aminopyrine are also evident. A proposed mechanism to explain this combination of findings is a defective microsomal membrane. To examine the 'matrix' of Gunn microsomal membranes, hepatic microsomes were isolated from Gunn (jj) and outbred Wistar (JJ) rats and were studied by electron paramagnetic resonance spectroscopy of 7-doxylstearic and 12-doxylstearic acid probes, fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene, glucose-6-phosphatase activity vs. temperature, and lipid analysis. The data indicate several factors related to lipid bilayer order do not differ in microsomes from jj and JJ. 相似文献
4.
Daren Lee Seth Ruffins Queenie Ng Nikhil Sane Steve Anderson Arthur Toga 《BMC bioinformatics》2010,11(1):608
Background
Digital atlases provide a common semantic and spatial coordinate system that can be leveraged to compare, contrast, and correlate data from disparate sources. As the quality and amount of biological data continues to advance and grow, searching, referencing, and comparing this data with a researcher's own data is essential. However, the integration process is cumbersome and time-consuming due to misaligned data, implicitly defined associations, and incompatible data sources. This work addressing these challenges by providing a unified and adaptable environment to accelerate the workflow to gather, align, and analyze the data. 相似文献5.
6.
7.
The effects of Heterosigma akashiwo on juvenile Oncorhynchus tshawytscha and its implications for fish culture 总被引:2,自引:0,他引:2
E. A. Black J.N. C. Whyth J. W. Bagshaw N. G. Ginther 《Zeitschrift fur angewandte Ichthyologie》1991,7(3):168-175
The effects of natural blooms of Heterosigma akashiwo on freshwater-and saltwater-acclimated juvenile chinook salmon were assessed. Rates of fish mortality in the blooms were independent of acclimation of fish to seawater and the ambient oxygen levels, but were dependent on concentration of algae and ambient water temperatures. No pathological abnormality to gills or other internal organs in the fish were evident. Aeration or oxygenation of fish cages did not enhance or inhibit fish survival in a H. akashiwo bloom. Cause of death was considered to be due to a labile ichthyotoxic agent. 相似文献
8.
9.
10.
Eileen M. Proctor Judith L. Isaac-Renton William B. Robertson William A. Black 《CMAJ》1985,133(9):876-878
A survey was done of Canadians who had been interned by the Japanese during World War II to assess the prevalence of latent infection with Strongyloides stercoralis in this group. Packages containing three mail-in kits and a questionnaire were sent to 992 men, 694 (70%) of whom responded. Larvae were found in the stool specimens of four of the respondents. Examination of stool specimens after formalin-ether concentration was the most successful method of detecting Strongyloides larvae. The Baermann concentration technique yielded negative results in all four men. Three of the four cases of strongyloidiasis were detected after sampling of three fecal specimens. In the fourth case additional specimens were requested on the basis of data derived from the questionnaire. The most frequently cited clinical manifestations were abdominal pain, weight loss, diarrhea and rashes. 相似文献