全文获取类型
收费全文 | 4653篇 |
免费 | 419篇 |
国内免费 | 2篇 |
出版年
2022年 | 30篇 |
2021年 | 59篇 |
2020年 | 54篇 |
2019年 | 59篇 |
2018年 | 48篇 |
2017年 | 65篇 |
2016年 | 112篇 |
2015年 | 169篇 |
2014年 | 205篇 |
2013年 | 257篇 |
2012年 | 336篇 |
2011年 | 332篇 |
2010年 | 204篇 |
2009年 | 190篇 |
2008年 | 263篇 |
2007年 | 268篇 |
2006年 | 253篇 |
2005年 | 254篇 |
2004年 | 257篇 |
2003年 | 221篇 |
2002年 | 230篇 |
2001年 | 63篇 |
2000年 | 47篇 |
1999年 | 71篇 |
1998年 | 64篇 |
1997年 | 56篇 |
1996年 | 38篇 |
1995年 | 38篇 |
1994年 | 30篇 |
1993年 | 51篇 |
1992年 | 34篇 |
1991年 | 37篇 |
1990年 | 34篇 |
1989年 | 39篇 |
1988年 | 27篇 |
1987年 | 24篇 |
1986年 | 28篇 |
1985年 | 28篇 |
1984年 | 30篇 |
1983年 | 25篇 |
1982年 | 27篇 |
1981年 | 24篇 |
1980年 | 19篇 |
1979年 | 24篇 |
1978年 | 19篇 |
1977年 | 22篇 |
1976年 | 21篇 |
1974年 | 16篇 |
1973年 | 24篇 |
1968年 | 15篇 |
排序方式: 共有5074条查询结果,搜索用时 453 毫秒
131.
The cost of managing 114 adult haemophiliacs in the west of Scotland was assessed for the period 1 March 1971 to 28 February 1974. Altogether 23 of them (20%) accounted for 80% of the resources used. The cost of hospital treatment of these patients during the period was compared with the predicted cost of home treatment, given the availability of freeze-dried factor VIII concentrate in sufficient amounts. We calculate that adequate on-demand home treatment would cost only 16% more than the present treatment, which is substantially less efficient. 相似文献
132.
133.
134.
135.
136.
137.
There have been several reports that individuals with Fragile X syndrome (FXS) and animal models of FXS have communication deficits. The present study utilized two different call classification taxonomies to examine the sex‐specificity of ultrasonic vocalization (USV) production on postnatal day (PD8) in the FVB strain of Fmr1 knockout (KO) mice. One classification protocol requires the investigator to score each call by hand, while the other protocol uses an automated algorithm. Results using the hand‐scoring protocol indicated that male Fmr1 KO mice exhibited longer calls (P = .03) than wild types on PD8. Male KOs also produced fewer complex, composite, downward, short and two‐syllable call‐types, as well as more frequency steps and chevron call‐types. Female heterozygotes exhibited no significant changes in acoustic or temporal aspects of calls, yet showed significant changes in call‐type production proportions across two different classification taxonomies (P < .001). They exhibited increased production of harmonic and frequency steps calls, as well as fewer chevron, downward and short calls. According to the second high‐throughput analysis, female heterozygotes produced significantly fewer single‐type and more multiple‐type syllables, unlike male KOs that showed no changes in these aspects of syllable production. Finally, we correlated both scoring methods and found a high level of correlation between the two methods. These results contribute further knowledge of sex differences in USV calling behavior for Fmr1 heterozygote and KO mice and provide a foundation for the use of high‐throughput analysis of neonatal USVs. 相似文献
138.
Seymour Colleen L. Milton Suzanne J. Altwegg Res Joseph Grant S. Dean W. Richard J. 《Ecosystems》2020,23(1):175-187
Ecosystems - Addition of nitrogen (N) to rangeland that has been degraded through overgrazing or drought can hasten vegetation recovery. Additional N may influence temporal stability of vegetation... 相似文献
139.
Suzanne M. Marselis Katharine Abernethy Alfonso Alonso John Armston Timothy R. Baker Jean‐Francois Bastin Jan Bogaert Doreen S. Boyd Pascal Boeckx David F. R. P. Burslem Robin Chazdon David B. Clark David Coomes Laura Duncanson Steven Hancock Ross Hill Chris Hopkinson Elizabeth Kearsley James R. Kellner David Kenfack Nicolas Labrire Simon L. Lewis David Minor Herv Memiaghe Abel Monteagudo Reuben Nilus Michael O'Brien Oliver L. Phillips John Poulsen Hao Tang Hans Verbeeck Ralph Dubayah 《Global Ecology and Biogeography》2020,29(10):1799-1816
140.