全文获取类型
收费全文 | 963篇 |
免费 | 72篇 |
国内免费 | 2篇 |
专业分类
1037篇 |
出版年
2024年 | 4篇 |
2023年 | 6篇 |
2022年 | 22篇 |
2021年 | 45篇 |
2020年 | 31篇 |
2019年 | 45篇 |
2018年 | 40篇 |
2017年 | 33篇 |
2016年 | 36篇 |
2015年 | 53篇 |
2014年 | 59篇 |
2013年 | 74篇 |
2012年 | 71篇 |
2011年 | 84篇 |
2010年 | 41篇 |
2009年 | 34篇 |
2008年 | 37篇 |
2007年 | 41篇 |
2006年 | 33篇 |
2005年 | 23篇 |
2004年 | 22篇 |
2003年 | 18篇 |
2002年 | 18篇 |
2001年 | 19篇 |
2000年 | 12篇 |
1999年 | 16篇 |
1998年 | 3篇 |
1997年 | 6篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 8篇 |
1991年 | 6篇 |
1990年 | 11篇 |
1989年 | 4篇 |
1988年 | 12篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1975年 | 3篇 |
1974年 | 6篇 |
1973年 | 3篇 |
1965年 | 1篇 |
排序方式: 共有1037条查询结果,搜索用时 12 毫秒
121.
Chaudhari Diptaraj Kiran Shashi Choudhary Ashish Silveira Kris Narwade Nitin Dhotre Dhiraj Khazir Jabeena Mir Bilal Ahmad Shouche Yogesh S. Rahi Praveen 《International microbiology》2023,26(2):257-267
International Microbiology - Indian lotus (Nelumbo nucifera) is one of the dominant aquatic plants cultivated in Dal Lake, situated at 1586 m above mean sea level (MSL) in the northeast of... 相似文献
122.
Shiedlin A Bigelow R Christopher W Arbabi S Yang L Maier RV Wainwright N Childs A Miller RJ 《Biomacromolecules》2004,5(6):2122-2127
Sodium hyaluronate (HA) is widely distributed in extracellular matrixes and can play a role in orchestrating cell function. Consequently, many investigators have looked at the effect of exogenous HA on cell behavior in vitro. HA can be isolated from several sources (e.g., bacterial, rooster comb, umbilical cord) and therefore can possess diverse impurities. This current study compares the measured impurities and the differences in biological activity between HA preparations from these sources. It was demonstrated that nucleic acid and protein content was highest in human umbilical cord and bovine vitreous HA and was low in bacterial and rooster comb HA. Macrophages exposed to human umbilical cord HA produced significantly higher amounts of TNF-alpha relative to control or bacterial-derived HA. These results indicate that the source of HA should be considered due to differences in the amounts and types of contaminants that could lead to widely different behaviors in vitro and in vivo. 相似文献
123.
Showket Ahmad Dar Samy Sayed Mohamed El-Sharnouby Muneer Ahmad Sofi Mudasir Hassan Rizwan Rashid Zahoor Ahmad Dar Sajad Hussain Mir Sayed-Ashraf Elarrnaouty Saad H.D. Masry Ivana Tlak Gajger 《Saudi Journal of Biological Sciences》2021,28(7):3720-3726
This paper represents an attempt to investigate the mating behaviour of Symmorphus allobrogus, explaining the willingness of male to mount and copulate. The male displays including mode and frequency of antennation and position while copulating, the displays further comprises of intensity and frequency of rejecting behaviour. The presence of the male’s copulatory and postcopulatory courtship studies, understands the maintenance of monandry. The wasp has numerous secondary sexual characters, and the mating behaviour follows a phyletic and the specific sexual mating characters in context of sexual selection. The duration of mating phases and the number of male antennation series during precopulatory, copulatory and postcopulatory phases of mounting, differs significantly. Mating success depends mostly on the activities of male in the premounting phase and the behaviour of both sexes has a roughly equal importance for it in precopulatory phase. While during copulation, activity of male has little influence on its duration; however, behaviour of female has crucial effect, inducing its earlier termination. 相似文献
124.
125.
Length–weight relationship of two fish species from Poonch River,Western Indian Himalaya: Glyptothorax kashmirensis (Hora, 1923) and Crossocheilus diplochilus (Heckel, 1838) 下载免费PDF全文
N. K. Sharma R. Singh N. N. Pandey M. S. Akhtar J. I. Mir 《Zeitschrift fur angewandte Ichthyologie》2015,31(6):1144-1145
This study provides the first report of length–weight relationships (LWRs) for two fish species, Glyptothorax kashmirensis and Crossocheilus diplochilus, collected from the Poonch River, one of the lesser tributaries to the Indus basin in India. New maximum length records are reported for both species. 相似文献
126.
Elevated atmospheric [CO2] can dramatically increase wheat yields in semi‐arid environments and buffer against heat waves 下载免费PDF全文
Glenn J. Fitzgerald Michael Tausz Garry O'Leary Mahabubur R. Mollah Sabine Tausz‐Posch Saman Seneweera Ivan Mock Markus Löw Debra L. Partington David McNeil Robert M. Norton 《Global Change Biology》2016,22(6):2269-2284
Wheat production will be impacted by increasing concentration of atmospheric CO2 [CO2], which is expected to rise from about 400 μmol mol?1 in 2015 to 550 μmol mol?1 by 2050. Changes to plant physiology and crop responses from elevated [CO2] (e[CO2]) are well documented for some environments, but field‐level responses in dryland Mediterranean environments with terminal drought and heat waves are scarce. The Australian Grains Free Air CO2 Enrichment facility was established to compare wheat (Triticum aestivum) growth and yield under ambient (~370 μmol?1 in 2007) and e[CO2] (550 μmol?1) in semi‐arid environments. Experiments were undertaken at two dryland sites (Horsham and Walpeup) across three years with two cultivars, two sowing times and two irrigation treatments. Mean yield stimulation due to e[CO2] was 24% at Horsham and 53% at Walpeup, with some treatment responses greater than 70%, depending on environment. Under supplemental irrigation, e[CO2] stimulated yields at Horsham by 37% compared to 13% under rainfed conditions, showing that water limited growth and yield response to e[CO2]. Heat wave effects were ameliorated under e[CO2] as shown by reductions of 31% and 54% in screenings and 10% and 12% larger kernels (Horsham and Walpeup). Greatest yield stimulations occurred in the e[CO2] late sowing and heat stressed treatments, when supplied with more water. There were no clear differences in cultivar response due to e[CO2]. Multiple regression showed that yield response to e[CO2] depended on temperatures and water availability before and after anthesis. Thus, timing of temperature and water and the crop's ability to translocate carbohydrates to the grain postanthesis were all important in determining the e[CO2] response. The large responses to e[CO2] under dryland conditions have not been previously reported and underscore the need for field level research to provide mechanistic understanding for adapting crops to a changing climate. 相似文献
127.
In vivo electroporation of skeletal muscle: threshold, efficacy and relation to electric field distribution. 总被引:10,自引:0,他引:10
J Gehl T H Sorensen K Nielsen P Raskmark S L Nielsen T Skovsgaard L M Mir 《Biochimica et biophysica acta》1999,1428(2-3):233-240
In vivo electroporation is increasingly being used to deliver small molecules as well as DNA to tissues. The aim of this study was to quantitatively investigate in vivo electroporation of skeletal muscle, and to determine the threshold for permeabilization. We designed a quantitative method to study in vivo electroporation, by measuring uptake of (51)Cr-EDTA. As electrode configuration influences electric field (E-field) distribution, we developed a method to calculate this. Electroporation of mouse muscle tissue was investigated using either external plate electrodes or internal needle electrodes placed 4 mm apart, and eight pulses of 99 micros duration at a frequency of 1 Hz. The applied voltage to electrode distance ratio was varied from 0 to 2.0 kV/cm. We found that: (1) the threshold for permeabilization of skeletal muscle tissue using short duration pulses was at an applied voltage to electrode distance ratio of 0.53 kV/cm (+/-0.03 kV/cm), corresponding to an E-field of 0.45 kV/cm; (2) there were two phases in the uptake of (51)Cr-EDTA, the first indicating increasing permeabilization and the second indicating beginning irreversible membrane damage; and (3) the calculated E-field distribution was more homogeneous for plate than for needle electrodes, which was reflected in the experimental results. 相似文献
128.
Analysis of length‐weight relationship of sympatric hill stream teleosts Barilius bendelisis (Hamilton, 1807) and Barilius vagra (Hamilton, 1822) from Garhwal Himalaya,India 下载免费PDF全文
The present study describes the length–weight relationships (LWRs) of two important ornamental hill stream fishes, Barilius bendelisis and Barilius vagra (Hamilton), of northern India. A total of 630 specimens were collected from January to June 2011 in a spring‐fed stream in Garhwal Himalaya, India. Information regarding LWRs of these species was not yet available in FishBase. 相似文献
129.
Michel Wright Catherine Albertini Viviane Planques Isabelle Salles Bernard Ducommun Catherine Gely Haleh Akhavan-Niaki Luis Mir Andr Moisand Marie-Louise Oustrin 《Biology of the cell / under the auspices of the European Cell Biology Organization》1988,63(2):239-248
Summary— The amoebae of the myxomycete Physarum polycephalum are of interest in order to analyze the morphogenesis of the microtubule and microfilament cytoskeleton during cell cycle and flagellation. The amoebal interphase microtubule cytoskeleton consists of 2 distinct levels of organization, which correspond to different physiological roles. The first level is composed of the 2 kinetosomes or centrioles and their associated structures. The anterior and posterior kinetosomes forming the anterior and posterior flagella are morphologically distinguishable. Each centriole plays a role in the morphogenesis of its associated satellites and specific microtubule arrays. The 2 distinct centrioles correspond to the 2 successive maturation stages of the pro-centrioles which are built during prophase. The second level of organization consists of a prominent microtubule organizing center (mtoc 1) to which the anterior centriole is attached at least during interphase. This mtoc plays a role in the formation of the mitotic pole. These observations based on ultrastructural and physiological analyses of the amoebal cystoskeleton are now being extended to the biochemical level. The complex formed by the 2 centrioles and the mtoc 1 has been purified without modifying the microtubule-nucleating activity of the mtoc 1. Several microtubule-associated proteins have been characterized by their ability to bind taxol-stabilized microtubules. Their functions (e.g., microtubule assembly, protection of microtubules against dilution or cold treatment, phosphorylating and ATPase activities) are under investigation. These biochemical approaches could allow in vitro analysis of the morphogenesis of the amoebal microtubule cytoskeleton. 相似文献
130.
The social amoeba Dictyostelium discoideum, a powerful paradigm provides clear insights into the regulation of growth and development. In addition to possessing complex individual cellular functions like a unicellular eukaryote, D. discoideum cells face the challenge of multicellular development. D. discoideum undergoes a relatively simple differentiation process mainly by cAMP mediated pathway. Despite this relative simplicity, the regulatory signaling pathways are as complex as those seen in metazoan development. However, the introduction of restriction-enzyme-mediated integration (REMI) technique to produce developmental gene knockouts has provided novel insights into the discovery of signaling molecules and their role in D. discoideum development. Cell cycle phase is an important aspect for differentiation of D. discoideum, as cells must reach a specific stage to enter into developmental phase and specific cell cycle regulators are involved in arresting growth phase genes and inducing the developmental genes. In this review, we present an overview of the signaling molecules involved in the regulation of growth to differentiation transition (GDT), molecular mechanism of early developmental events leading to generation of cAMP signal and components of cAMP relay system that operate in this paradigm. 相似文献