全文获取类型
收费全文 | 2240篇 |
免费 | 133篇 |
国内免费 | 1篇 |
专业分类
2374篇 |
出版年
2023年 | 11篇 |
2022年 | 19篇 |
2021年 | 50篇 |
2020年 | 18篇 |
2019年 | 32篇 |
2018年 | 56篇 |
2017年 | 52篇 |
2016年 | 77篇 |
2015年 | 121篇 |
2014年 | 112篇 |
2013年 | 162篇 |
2012年 | 207篇 |
2011年 | 147篇 |
2010年 | 120篇 |
2009年 | 79篇 |
2008年 | 119篇 |
2007年 | 118篇 |
2006年 | 105篇 |
2005年 | 100篇 |
2004年 | 68篇 |
2003年 | 65篇 |
2002年 | 64篇 |
2001年 | 58篇 |
2000年 | 58篇 |
1999年 | 38篇 |
1998年 | 16篇 |
1997年 | 13篇 |
1996年 | 7篇 |
1995年 | 9篇 |
1994年 | 9篇 |
1993年 | 11篇 |
1992年 | 19篇 |
1991年 | 22篇 |
1990年 | 19篇 |
1989年 | 15篇 |
1988年 | 16篇 |
1987年 | 16篇 |
1986年 | 7篇 |
1985年 | 16篇 |
1984年 | 9篇 |
1983年 | 8篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1979年 | 10篇 |
1978年 | 9篇 |
1977年 | 7篇 |
1976年 | 8篇 |
1975年 | 7篇 |
1973年 | 7篇 |
1967年 | 4篇 |
排序方式: 共有2374条查询结果,搜索用时 15 毫秒
991.
992.
José Nicolau Douglas Nesadal De Souza Alyne Simões 《Cell biochemistry and function》2009,27(3):128-134
Diabetes has been implicated in the dryness of the mouth, loss of taste sensation, sialosis, and other disorders of the oral cavity, by impairment of the salivary glands. The aim of the present study was to examine the plasma membrane, microsomal, and homogenate Ca2+‐ATPase activity in the rat submandibular and parotid salivary glands of streptozotocin‐induced diabetes. We have also examined the influence of the acidosis state on this parameter. Diabetes was induced by an intraperitoneal injection of streptozotocin and acidosis was induced by daily injection of NH4Cl. At 15 and 30 days after diabetes induction, the animals were euthanized and the submandibular and parotid salivary glands were removed and analyzed. Ca2+‐ATPase (total, independent, and dependent) was determined in the homogenate, microsomal, and plasma membranes of the salivary glands of diabetic and control rats. Calcium concentration was also determined in the glands and showed to be higher in the diabetic animals. Ca2+‐ATPase activity was found to be reduced in all cell fractions studied in the diabetic animals compared with control. Similar results were obtained for the submandibular salivary glands of acidotic animals; however in the parotid salivary glands it was found an increase in the enzyme activity. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
993.
994.
995.
996.
Sonia Gabriela Ortiz‐Maciel Alejandro Salinas‐Melgoza Simón Octavio Valdéz‐Juárez Leonel Lopez‐Toledo Ernesto Enkerlin‐Hoeflich 《Ibis》2014,156(2):299-310
Stochastic and catastrophic events may strongly impact the dynamics of wild populations. Annual fluctuations in rainfall may affect parrot populations, but few studies address the impact of other stochastic or catastrophic events on their population dynamics. The Maroon‐fronted Parrot Rhynchopsitta terrisi is an endangered species that nests colonially in cavities and crevices in limestone cliffs. From 1995 to 2010, we quantified Parrot attendance at nesting colonies throughout its breeding range, and reproductive output of nesting Parrots from 1997 to 2010 at the two most important nesting colonies. There was significant variation among colonies in the number of cavities occupied by Parrots each year. Rainfall significantly influenced both the number of occupied cavities and productivity, which declined after very dry years. Natural unpredictable events such as hurricanes did not modify the nesting activity of Maroon‐fronted Parrots at breeding colonies. However, wildfires increased in dry years, negatively affecting attendance at breeding colonies. The Maroon‐fronted Parrot may overcome the impacts of climatic variability, natural stochastic processes, and human‐induced catastrophic events by using nesting colonies as a network of resources throughout the breeding range. Given the current trends in climate change, it is likely the species may suffer stronger and more frequent unpredictable catastrophic events, potentially putting at risk its survival in the long term. 相似文献
997.
Solution structures and model membrane interactions of Ctriporin,an anti‐methicillin‐resistant Staphylococcus aureus Peptide from Scorpion Venom 下载免费PDF全文
Susmita Bandyopadhyay Ryan Loh Junjie Brendan Lim R. Sanjeev Woon Yong Xin Chong Kok Yee Sim Ming Hui Melodies Nicole Yow J. Sivaraman Chiradip Chatterjee 《Biopolymers》2014,101(12):1143-1153
Ctriporin peptide (Ctr), a novel antimicrobial peptide isolated from the venom of the scorpion Chaerilus tricostatus, shows a broad‐spectrum of antimicrobial activity and is able to inhibit antibiotic resistant pathogens, including Methicillin resistant Staphylococcus aureus, Methicillin Resistant Coagulase‐negative Staphylococcus, and Penicillin Resistant Staphylococcus epidermidis strains. To understand the active conformation of the Ctr peptide in membranes, we have investigated the interaction of Ctr with the negatively charged and zwitterionic membrane‐mimetic micelles such as sodium dodecyl sulphate (SDS) and n‐dodecylphosphocholine (DPC), respectively. The interactions were studied using fluorescence and circular dichroism (CD) spectroscopy. Fluorescence experiments revealed that the N‐terminus tryptophan residue of Ctr interacted with the hydrophobic core of the membrane mimicking micelles. The CD results suggest that interactions with membrane‐mimetic micelles induce an α‐helix conformation in Ctr. Moreover, we have determined the solution structures of Ctr in SDS and DPC micelles using nuclear magnetic resonance (NMR) spectroscopy. The structural comparison of Ctr in the presence of SDS and DPC micelles showed significant conformational changes. The observed structural differences of Ctr in anionic versus zwitterionic membrane‐mimetic micelles suggest that the mode of interaction of this peptide may be different in two environments which may account for its ability to differentiate bacterial and eukaryotic cell membrane. © 2014 Wiley Periodicals, Inc. Biopolymers 101: 1143–1153, 2014. 相似文献
998.
999.
Helder-José Erasmo Garcia Mendes Nancy Marques Carneiro Manuel Jesus Simões Edna Freymüller 《Zoomorphology》2014,133(2):237-243
The histophysiology of both brown and yellow paracloacal glands of control animals from wild populations was analyzed in the breeding and non-breeding seasons and in oophorectomized animals. The effect of estrogens on the scent glands of female Metachirus nudicaudatus was investigated. Radioimmunoassay indicated that estradiol levels in the breeding season were high, while those in the non-breeding season and oophorectomized had minute amounts. No apparent change in gland volume was observed in the various animal groups. Light microscopy showed a wide variation in the number of layers of the holocrine secretory epithelium of the major (brown) gland between the breeding (1–7) and non-breeding season (8–19) and in oophorectomized (8–18) animals. The minor (yellow) gland showed the most evident variation: the holocrine epithelium was restricted to the basal layer in the breeding season, but was restored and exhibited up to eight layers in the non-breeding season and in oophorectomized females. The mean cellular area of the secretory holocrine epithelium in the breeding season was smaller than in the non-breeding period and in castrated animals. On the other hand, the mean cellular areas of tubular glands inserted in both yellow and brown glands in the breeding season were larger than those in the non-breeding season and after castration. The results consistently indicate that the glandular volumes of yellow and brown glands do not depend on estrogens, whereas the holocrine secretory epithelium and tubular glands of both are estrogenic modulation. 相似文献
1000.
ARRY‐334543 Reverses Multidrug Resistance by Antagonizing the Activity of ATP‐Binding Cassette Subfamily G Member 2 下载免费PDF全文