全文获取类型
收费全文 | 5178篇 |
免费 | 395篇 |
国内免费 | 7篇 |
出版年
2023年 | 18篇 |
2022年 | 36篇 |
2021年 | 85篇 |
2020年 | 51篇 |
2019年 | 70篇 |
2018年 | 77篇 |
2017年 | 87篇 |
2016年 | 148篇 |
2015年 | 234篇 |
2014年 | 272篇 |
2013年 | 316篇 |
2012年 | 371篇 |
2011年 | 361篇 |
2010年 | 229篇 |
2009年 | 257篇 |
2008年 | 332篇 |
2007年 | 304篇 |
2006年 | 338篇 |
2005年 | 297篇 |
2004年 | 305篇 |
2003年 | 289篇 |
2002年 | 262篇 |
2001年 | 68篇 |
2000年 | 43篇 |
1999年 | 63篇 |
1998年 | 58篇 |
1997年 | 32篇 |
1996年 | 38篇 |
1995年 | 39篇 |
1994年 | 44篇 |
1993年 | 38篇 |
1992年 | 39篇 |
1991年 | 28篇 |
1990年 | 22篇 |
1989年 | 24篇 |
1988年 | 22篇 |
1987年 | 13篇 |
1986年 | 21篇 |
1985年 | 22篇 |
1984年 | 27篇 |
1983年 | 14篇 |
1982年 | 14篇 |
1981年 | 16篇 |
1980年 | 18篇 |
1979年 | 11篇 |
1978年 | 15篇 |
1977年 | 15篇 |
1976年 | 14篇 |
1975年 | 10篇 |
1974年 | 9篇 |
排序方式: 共有5580条查询结果,搜索用时 15 毫秒
171.
Ken Fukami Kiyoshi Kawai Sayaka Takeuchi Yoshito Harada Yoshio Hagura 《Food biophysics》2016,11(4):410-416
To understand the fundamental physical properties of calcium maltobionate (MBCa), its water sorption isotherm, glass transition temperature (T g), and viscosity (η) were investigated and compared with those of maltobionic acid (MBH) and maltose. Although amorphous maltose crystalized at water activity (a w) higher than 0.43, MBCa and MBH maintained an amorphous state over the whole a w range. In addition, MBCa had a higher T g and greater resistance to water plasticizing than MBH and maltose. These properties of MBCa likely originate from the strong interaction between MBCa and water induced by electrostatic interactions. Moreover, the effects of temperature and water content on η of an aqueous MBCa solution were evaluated, and its behavior was described using a semi-empirical approach based on a combination of T g extrapolated by the Gordon-Taylor equation and a non-Arrhenius formula known as the Vogel–Fulcher–Tammann equation. This result will be useful for understating the effect of MBCa addition on the solution’s properties. 相似文献
172.
Tongwu Zhang Ken Dutton‐Regester Kevin M. Brown Nicholas K. Hayward 《Pigment cell & melanoma research》2016,29(3):266-283
Somatic mutation analysis of melanoma has been performed at the single gene level extensively over the past several decades. This has provided considerable insight into the critical pathways controlling melanoma initiation and progression. During the last 5 yr, next‐generation sequencing (NGS) has enabled even more comprehensive mutational screening at the level of multigene panels, exomes and genomes. These studies have uncovered many new and unexpected players in melanoma development. The recent landmark study from The Cancer Genome Atlas (TCGA) consortium describing the genomic architecture of 333 cutaneous melanomas provides the largest and broadest analysis to date on the somatic aberrations underlying melanoma genesis. It thus seems timely to review the mutational landscape of melanoma and highlight the key genes and cellular pathways that appear to drive this cancer. 相似文献
173.
174.
Habitat fragmentation reduces the available habitat area and increases both the distance between fragments and the amount of fragment edges. Therefore, there are more probabilities of plant population size reduction and species extinction. In the same way, biotic and abiotic changes associated with forest fragmentation can dramatically alter plant growth and phenological patterns. We conducted a 3-year study to analyze effects of habitat fragmentation and seasonal variation on host plant quality (quantity of leaves, diameter at breast height, tree height), gall abundance and species richness in a temperate oak forest. Our results show that host plant quality was significantly higher in isolated oaks and small fragments, increasing the abundance and species richness of oak gall wasp species in most fragmented habitats. Oak canopy cover is altered by forest fragmentation, there being higher production of leaves on trees that are more exposed to fragmentation, and can provide important resources for maintaining gall wasp species diversity in a fragmented landscape. We found higher gall wasp richness and abundance in autumn than in the spring, which matches with the higher quantity of leaves in this season. 相似文献
175.
Christian Montag Elisabeth Hahn Martin Reuter Frank M. Spinath Ken Davis Jaak Panksepp 《PloS one》2016,11(3)
The present study investigated for the first time the relative importance of genetics and environment on individual differences in primary emotionality as measured with the Affective Neuroscience Personality Scales (ANPS) by means of a twin-sibling study design. In N = 795 participants (n = 303 monozygotic twins, n = 172 dizygotic twins and n = 267 non-twin full siblings), moderate to strong influences of genetics on individual differences in these emotional systems are observed. Lowest heritability estimates are presented for the SEEKING system (33%) and highest for the PLAY system (69%). Further, multivariate genetic modeling was applied to the data showing that associations among the six ANPS scales were influences by both, a genetic as well as an environmental overlap between them. In sum, the study underlines the usefulness of the ANPS for biologically oriented personality psychology research. 相似文献
176.
Early Weight Loss with Liraglutide 3.0 mg Predicts 1‐Year Weight Loss and is Associated with Improvements in Clinical Markers
下载免费PDF全文
![点击此处可从《Obesity (Silver Spring, Md.)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
177.
Randomized controlled trial of a nationally available weight control program tailored for adults with type 2 diabetes
下载免费PDF全文
![点击此处可从《Obesity (Silver Spring, Md.)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Patrick M. O'Neil Peter W. Tuerk Lynne E. Becker Thomas A. Wadden Ken Fujioka Priscilla L. Hollander Robert F. Kushner W. Timothy Garvey Domenica M. Rubino Robert J. Malcolm Daniel Weiss William J. Raum Jonny L. Salyer Kathie L. Hermayer Jan L. Veliko Nicoleta D. Sora 《Obesity (Silver Spring, Md.)》2016,24(11):2269-2277
178.
Hirotsugu Ohkubo Yoshihiro Kanemitsu Takehiro Uemura Osamu Takakuwa Masaya Takemura Ken Maeno Yutaka Ito Tetsuya Oguri Nobutaka Kazawa Ryuji Mikami Akio Niimi 《PloS one》2016,11(3)
BackgroundAlthough several computer-aided computed tomography (CT) analysis methods have been reported to objectively assess the disease severity and progression of idiopathic pulmonary fibrosis (IPF), it is unclear which method is most practical. A universal severity classification system has not yet been adopted for IPF.ObjectiveThe purpose of this study was to test the correlation between quantitative-CT indices and lung physiology variables and to determine the ability of such indices to predict disease severity in IPF.MethodsA total of 27 IPF patients showing radiological UIP pattern on high-resolution (HR) CT were retrospectively enrolled. Staging of IPF was performed according to two classification systems: the Japanese and GAP (gender, age, and physiology) staging systems. CT images were assessed using a commercially available CT imaging analysis workstation, and the whole-lung mean CT value (MCT), the normally attenuated lung volume as defined from −950 HU to −701 Hounsfield unit (NL), the volume of the whole lung (WL), and the percentage of NL to WL (NL%), were calculated.ResultsCT indices (MCT, WL, and NL) closely correlated with lung physiology variables. Among them, NL strongly correlated with forced vital capacity (FVC) (r = 0.92, P <0.0001). NL% showed a large area under the receiver operating characteristic curve for detecting patients in the moderate or advanced stages of IPF. Multivariable logistic regression analyses showed that NL% is significantly more useful than the percentages of predicted FVC and predicted diffusing capacity of the lungs for carbon monoxide (Japanese stage II/III/IV [odds ratio, 0.73; 95% confidence intervals (CI), 0.48 to 0.92; P < 0.01]; III/IV [odds ratio. 0.80; 95% CI 0.59 to 0.96; P < 0.01]; GAP stage II/III [odds ratio, 0.79; 95% CI, 0.56 to 0.97; P < 0.05]).ConclusionThe measurement of NL% by threshold-based volumetric CT analysis may help improve IPF staging. 相似文献
179.
180.
Alarm communication is a key adaptation that helps social groups resist predation and rally defenses. In Asia, the world’s largest hornet, Vespa mandarinia, and the smaller hornet, Vespa velutina, prey upon foragers and nests of the Asian honey bee, Apis cerana. We attacked foragers and colony nest entrances with these predators and provide the first evidence, in social insects, of an alarm signal that encodes graded danger and attack context. We show that, like Apis mellifera, A. cerana possesses a vibrational “stop signal,” which can be triggered by predator attacks upon foragers and inhibits waggle dancing. Large hornet attacks were more dangerous and resulted in higher bee mortality. Per attack at the colony level, large hornets elicited more stop signals than small hornets. Unexpectedly, stop signals elicited by large hornets (SS large hornet) had a significantly higher vibrational fundamental frequency than those elicited by small hornets (SS small hornet) and were more effective at inhibiting waggle dancing. Stop signals resulting from attacks upon the nest entrance (SS nest) were produced by foragers and guards and were significantly longer in pulse duration than stop signals elicited by attacks upon foragers (SS forager). Unlike SS forager, SS nest were targeted at dancing and non-dancing foragers and had the common effect, tuned to hornet threat level, of inhibiting bee departures from the safe interior of the nest. Meanwhile, nest defenders were triggered by the bee alarm pheromone and live hornet presence to heat-ball the hornet. In A. cerana, sophisticated recruitment communication that encodes food location, the waggle dance, is therefore matched with an inhibitory/alarm signal that encodes information about the context of danger and its threat level. 相似文献