全文获取类型
收费全文 | 2005篇 |
免费 | 234篇 |
国内免费 | 81篇 |
出版年
2022年 | 22篇 |
2021年 | 35篇 |
2020年 | 17篇 |
2019年 | 26篇 |
2018年 | 24篇 |
2017年 | 23篇 |
2016年 | 31篇 |
2015年 | 51篇 |
2014年 | 57篇 |
2013年 | 100篇 |
2012年 | 123篇 |
2011年 | 102篇 |
2010年 | 86篇 |
2009年 | 66篇 |
2008年 | 78篇 |
2007年 | 98篇 |
2006年 | 104篇 |
2005年 | 81篇 |
2004年 | 55篇 |
2003年 | 59篇 |
2002年 | 69篇 |
2001年 | 64篇 |
2000年 | 54篇 |
1999年 | 53篇 |
1998年 | 28篇 |
1997年 | 25篇 |
1996年 | 31篇 |
1995年 | 18篇 |
1994年 | 20篇 |
1993年 | 20篇 |
1992年 | 32篇 |
1991年 | 32篇 |
1990年 | 26篇 |
1989年 | 26篇 |
1988年 | 30篇 |
1987年 | 24篇 |
1985年 | 18篇 |
1984年 | 23篇 |
1982年 | 26篇 |
1979年 | 16篇 |
1977年 | 19篇 |
1974年 | 17篇 |
1973年 | 19篇 |
1959年 | 17篇 |
1958年 | 30篇 |
1955年 | 21篇 |
1954年 | 20篇 |
1953年 | 26篇 |
1952年 | 19篇 |
1950年 | 19篇 |
排序方式: 共有2320条查询结果,搜索用时 15 毫秒
91.
92.
93.
H E Schroeder U Schroeder G Santibánez-H 《The Pavlovian journal of biological science》1986,21(1):16-24
This study analyzes so-called hopeless gaggers, i.e., patients in whom dental treatment and wearing of a prosthesis produced a retching or vomiting reaction, in order to investigate the sources and properties of this pathologic reaction. In 35 patients, an anamnestic inquiry, a determination of the reflexogenic zone, a recording of the peripheral pattern of the pathologic reflex, and extinction training were performed. A group of six normal persons served as a comparison group. It was shown that patients, in comparison with normals, had an enlarged receptive field, were sensitive to a broader population of stimuli, and showed precursors and aftereffects of the retching-vomiting not found in normals. This pathologic reaction was the symptom of different psychopathologic processes, such as specific fear, repugnance-fear-based disturbances, diffuse anxiety, goal-directed behavior, depressive states and, at least in one case, visceral pathology. The various patients differed with respect to properties of the reaction as well as in the sensitivity to the extinction procedure. It is discussed that different integrative nervous processes play a role in the origin and development of the syndrome: activation of unconditional reflexes, activation of classic and instrumental conditional reflexes, activation of such reflexes by an increase of the reactivity level of specific and unspecific structures of the brain, generalization of stimuli, etc. 相似文献
94.
95.
96.
David C. Stoner Michael T. Anderson Cody A. Schroeder Cole A. Bleke Eric T. Thacker 《The Journal of wildlife management》2021,85(6):1062-1073
Free-roaming equids (i.e., feral horses [Equus caballus] and burros [Equus asinus]) are widely distributed and locally abundant across the rangelands of the western United States. The 1971 Wild Free Roaming Horse and Burro Act (WFRHBA) gave the Bureau of Land Management (BLM) and United States Forest Service (USFS) the legal authority to manage these animals on designated public lands. To fulfill this responsibility, federal agencies established an Appropriate Management Level (AML), defined as the number of horses or burros that can be sustained on a given management unit under prevailing environmental conditions and land uses. Although the WFRHBA specifies that feral equids must be managed in ecological balance with other land uses, including conservation of native wildlife, population control measures such as gathers, contraception, and adoptions have failed to keep pace with intrinsic growth rates. Over 80% of federally managed herds currently exceed prescribed population levels, making the potential for competition between native ungulates and feral equids a growing concern among state wildlife agencies. Mule deer (Odocoileus hemionus), pronghorn (Antilocapra americana), elk (Cervus canadensis), and bighorn sheep (Ovis canadensis) are of ecological and economic value to the states where they occur, and all exhibit some degree of distributional, habitat, or dietary overlap with horses or burros. Notwithstanding the scale of the problem, to date there have been no range-wide assessments of competition potential among native and feral ungulates for space, forage, or water. To address this need, we compiled demographic, jurisdictional, and species occurrence data collected from 2010–2019 by federal and state agencies. We used these data to map the distributions of 4 native ungulate species across federal equid management units (FEMUS) in 10 western states (n = 174). We then made within-state rankings of the 50 units that were ≥2 times over AML and encompassed ≥3 native ungulates. Collectively, FEMUs covered approximately 225,000 km2, representing 18% of all BLM and USFS lands in affected states. Each FEMU supported ≥1 native ungulate and 14% contained all 4. The degree of overlap between native and feral species varied by state, ranging from <1% for mule deer in Montana, to 40% for bighorn sheep in Nevada. Oregon had the largest proportion of units that supported all 4 native ungulates (58%), whereas Montana and New Mexico had the fewest equids, but all populations were over target densities. Despite the perception that the problem of equid abundance is limited to the Great Basin states, high intrinsic growth rates and social constraints on management practices suggest all affected states should monitor range conditions and native ungulate demography in areas where forage and water resources are limited and expanding equid populations are a concern. © 2021 The Wildlife Society. 相似文献
97.
98.
99.
100.
Bikash R. Pattnaik Sara Tokarz Matti P. Asuma Tyler Schroeder Anil Sharma Julie C. Mitchell Albert O. Edwards De-Ann M. Pillers 《PloS one》2013,8(8)
Snowflake Vitreoretinal Degeneration (SVD) is associated with the R162W mutation of the Kir7.1 inwardly-rectifying potassium channel. Kir7.1 is found at the apical membrane of Retinal Pigment Epithelial (RPE) cells, adjacent to the photoreceptor neurons. The SVD phenotype ranges from RPE degeneration to an abnormal b-wave to a liquid vitreous. We sought to determine how this mutation alters the structure and function of the human Kir7.1 channel. In this study, we expressed a Kir7.1 construct with the R162W mutation in CHO cells to evaluate function of the ion channel. Compared to the wild-type protein, the mutant protein exhibited a non-functional Kir channel that resulted in depolarization of the resting membrane potential. Upon co-expression with wild-type Kir7.1, R162W mutant showed a reduction of IKir7.1 and positive shift in ‘0’ current potential. Homology modeling based on the structure of a bacterial Kir channel protein suggested that the effect of R162W mutation is a result of loss of hydrogen bonding by the regulatory lipid binding domain of the cytoplasmic structure. 相似文献