全文获取类型
收费全文 | 10551篇 |
免费 | 1146篇 |
国内免费 | 1篇 |
出版年
2021年 | 121篇 |
2020年 | 81篇 |
2018年 | 109篇 |
2017年 | 90篇 |
2016年 | 197篇 |
2015年 | 285篇 |
2014年 | 308篇 |
2013年 | 405篇 |
2012年 | 515篇 |
2011年 | 508篇 |
2010年 | 334篇 |
2009年 | 316篇 |
2008年 | 406篇 |
2007年 | 464篇 |
2006年 | 410篇 |
2005年 | 426篇 |
2004年 | 404篇 |
2003年 | 395篇 |
2002年 | 399篇 |
2001年 | 279篇 |
2000年 | 244篇 |
1999年 | 203篇 |
1998年 | 135篇 |
1997年 | 113篇 |
1996年 | 117篇 |
1995年 | 127篇 |
1994年 | 128篇 |
1993年 | 99篇 |
1992年 | 181篇 |
1991年 | 157篇 |
1990年 | 155篇 |
1989年 | 158篇 |
1988年 | 144篇 |
1987年 | 142篇 |
1986年 | 115篇 |
1985年 | 116篇 |
1984年 | 132篇 |
1983年 | 115篇 |
1982年 | 134篇 |
1981年 | 104篇 |
1980年 | 110篇 |
1979年 | 122篇 |
1978年 | 111篇 |
1977年 | 97篇 |
1976年 | 111篇 |
1975年 | 105篇 |
1974年 | 106篇 |
1973年 | 105篇 |
1972年 | 89篇 |
1971年 | 76篇 |
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
1.
2.
Maurice Campbell 《BMJ (Clinical research ed.)》1948,2(4579):669-671
3.
Simon Rosenstein Harry D. Brown 《Biochimica et Biophysica Acta (BBA)/General Subjects》1980,629(1):195-198
Comparative assays were made in a spectrophotometer and a microcalorimeter for the reaction between acetylcholinesterase (EC 3.1.1.7) and acetylthiocholine. The rate of light absorbance change and the rate of heat flow were measured from similar and simultaneous reactions in spectrophotometer and microcalorimeter, respectively. At the enzyme activity levels studied, i.e., 0.05–0.15 I.U. in calorimetry and 1–4 I.U. in spectrophotometry, the reaction rates were linear and showed first-order kinetics. A highly significant positive correlation was seen between the two methods (r = 0.997). More importantly, spectrophotometric assay with acetylthiocholine (which utilized a secondary reaction with chromagen, dithiobisnitrobenzoic acid) stood in highly significant positive correlation with calorimetric assays (which did not require a chromagen) either with the same substrate (r = 0.976) or with acetylcholine (r = 0.900). It appears that microcalorimetry can be used in preference to spectrophotometry for enzyme kinetic studies to overcome the complexity of reaction mixture and interference problems and with the advantage of using natural substrates. 相似文献
4.
5.
6.
7.
8.
9.
Susan Morrison Grace John-Stewart John J. Egessa Sezi Mubezi Sylvia Kusemererwa Dennis K. Bii Nulu Bulya Francis Mugume James D. Campbell Jonathan Wangisi Elizabeth A. Bukusi Connie Celum Jared M. Baeten Partners PrEP Study Team 《PloS one》2015,10(10)
During an HIV-1 prevention clinical trial in East Africa, we observed 16 cases of primary HIV-1 infection in women coincident with pregnancy or breastfeeding. Nine of eleven pregnant women initiated rapid combination antiretroviral therapy (ART), despite having CD4 counts exceeding national criteria for ART initiation; breastfeeding women initiated ART or replacement feeding. Rapid ART initiation during primary HIV-1 infection during pregnancy and breastfeeding is feasible in this setting. 相似文献
10.
Brief admission of the new diabetic child and of a parent to an enlightened hospital for stabilisation, preliminary education, and familiarisation with hospital and community staff is well worth while. The greater the demand for constant control of the highest quality, the greater the need for a close understanding of the psychosocial factors concerned and for clinical skill. The nature of the home and the family relationships should in theory be available from the child''s general practitioner at the time of the first referral since he has so much information about the whole family. With the virtual disappearance, however, of mutual consultation in the patient''s home in many places, the opportunity for oral communication has declined, and availability on the telephone is not always easy. The busy general practitioner (far less an unknown physician from a deputising service without access to the records) has little time to write a comprehensive letter. In practice a relatively small hospital-based mobile team of specially experienced sisters who are keen to communicate in the home, the GP''s surgery, and the school makes a major contribution to the diabetic care of a young population vulnerable to major handicap in what should be the prime of life. Their cost effectiveness may be difficult to prove but it is not at all in doubt--especially when the sisters as in this area deal in the community with a wider range of chronic illnesses and handicaps in children. 相似文献