全文获取类型
收费全文 | 4908篇 |
免费 | 387篇 |
国内免费 | 5篇 |
出版年
2023年 | 14篇 |
2022年 | 8篇 |
2021年 | 75篇 |
2020年 | 51篇 |
2019年 | 67篇 |
2018年 | 76篇 |
2017年 | 86篇 |
2016年 | 145篇 |
2015年 | 227篇 |
2014年 | 266篇 |
2013年 | 307篇 |
2012年 | 366篇 |
2011年 | 354篇 |
2010年 | 226篇 |
2009年 | 250篇 |
2008年 | 325篇 |
2007年 | 297篇 |
2006年 | 326篇 |
2005年 | 290篇 |
2004年 | 297篇 |
2003年 | 279篇 |
2002年 | 254篇 |
2001年 | 57篇 |
2000年 | 35篇 |
1999年 | 59篇 |
1998年 | 51篇 |
1997年 | 35篇 |
1996年 | 25篇 |
1995年 | 32篇 |
1994年 | 38篇 |
1993年 | 33篇 |
1992年 | 37篇 |
1991年 | 24篇 |
1990年 | 21篇 |
1989年 | 20篇 |
1988年 | 16篇 |
1987年 | 13篇 |
1986年 | 16篇 |
1985年 | 17篇 |
1984年 | 22篇 |
1983年 | 17篇 |
1982年 | 15篇 |
1981年 | 16篇 |
1980年 | 20篇 |
1979年 | 11篇 |
1978年 | 9篇 |
1977年 | 13篇 |
1976年 | 12篇 |
1975年 | 10篇 |
1972年 | 6篇 |
排序方式: 共有5300条查询结果,搜索用时 187 毫秒
1.
2.
3.
Although systematic, quantitative assessment of environmental health risks is a staple of regulatory decision-making, complaints regarding its perceived failures and shortcomings are an intrinsic feature of the policy landscape. In this article, we (a) catalog the classic criticisms of conventional health risk assessment, (b) create a typology that orders the critiques according to their focus on either input errors or output biases, and (c) identify selected allegations that fall within each category. We also note that the risk assessment–risk management paradigm has evolved over the past several decades, partially in accordance with the general direction and spirit of these classic critiques. The debate continues today along familiar lines invoking the traditional critiques and rebuttals outlined here. 相似文献
4.
Ruxandra Ion L. Telvi Jean-Louis Chaussain Jacques Patrick Barbet Manoel Nunes Anne Safar Marie-Odile Réthoré Marc Fellous Ken McElreavey 《Human genetics》1998,102(2):151-156
In 46,XY individuals, testes are determined by the activity of the SRY gene (sex-determining region Y), located on the short arm of the Ychromosome. The other genetic components of the cascade
that leads to testis formation are unknown and may be located on the Xchromosome or on the autosomes. Evidence for the existence
of several loci associated with failure of male sexual development is indicated by reports of 46,XY gonadal dysgenesis associated
with structural abnormalities of the Xchromosome or of autosomes (chromosomes9, 10, 11 and 17). In this report, we describe
the investigation of a child presenting with multiple congenital abnormalities, mental retardation and partial testicular
failure. The patient had a homogeneous de novo 46,XY,inv dup(9)(pter→p24.1::p21.1 →p23.3::p24.1→qter) chromosome complement.
No deletion was found by either cytogenetic or molecular analysis. The SRY gene and DSS region showed no abnormalities. Southern blotting dosage analysis with 9p probes and fluorescent in situ hybridisation data
indicated that the distal breakpoint of the duplicated fragment was located at 9p24.1, proximal to the SNF2 gene. We therefore suggest that a gene involved in normal testicular development and/or maintenance is present at this position
on chromosome 9.
Received: 20 January 1997 / Accepted: 5 November 1997 相似文献
5.
6.
7.
8.
9.
Antoine Wystrach Sebastian Schwarz Patrick Schultheiss Guy Beugnon Ken Cheng 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2011,197(2):167-179
The Australian desert ant Melophorus bagoti often follows stereotypical routes through a cluttered landscape containing both distant panoramic views and obstacles (plants)
to navigate around. We created an artificial obstacle course for the ants between a feeder and their nest. Landmarks comprised
natural objects in the landscape such as logs, branches, and tussocks. Many ants travelled stereotypical routes home through
the obstacle course in training, threading repeatedly the same gaps in the landmarks. Manipulations altering the relations
between the landmarks and the surrounding panorama, however, affected the routes in two major ways. Both interchanging the
positions of landmarks (transpositions) and displacing the entire landmark set along with the starting position of the ants
(translations) (1) reduced the stereotypicality of the route, and (2) increased turns and meanders during travel. The ants
might have used the entire panorama in view-based travel, or the distal panorama might prime the identification and use of
landmarks en route. Despite the large data set, both options (not mutually exclusive) remain viable. 相似文献
10.