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61.
Roberta L. Millstein 《Journal of the history of biology》2008,41(2):339-367
Biologists and philosophers have been extremely pessimistic about the possibility of demonstrating random drift in nature,
particularly when it comes to distinguishing random drift from natural selection. However, examination of a historical case
– Maxime Lamotte’s study of natural populations of the land snail, Cepaea nemoralis in the 1950s – shows that while some pessimism is warranted, it has been overstated. Indeed, by describing a unique signature
for drift and showing that this signature obtained in the populations under study, Lamotte was able to make a good case for
a significant role for␣drift. It may be difficult to disentangle the causes of drift and selection acting in a population,
but it is not (always) impossible. 相似文献
62.
63.
Comocladia mayana, a new species of Anacardiaceae, is described, mapped and illustrated. The species is endemic to western Belize and adjacent
Guatemala and is restricted to semi-deciduous moist forest on karstic limestone formations. It differs from all other Comocladia species by the combination of entire to subentire, acuminate leaflets and tetramerous staminate flowers. 相似文献
64.
Mingyue Wang Pranab K Mukherjee Jyotsna Chandra Ali Abdul Lattif Thomas S McCormick Mahmoud A Ghannoum 《BMC microbiology》2008,8(1):31
Background
We have previously shown that supernatant from Candida albicans (CA) culture contains a Secretory Interleukin (IL)-12 Inhibitory Factor (CA-SIIF), which inhibits IL-12 production by human monocytes. However, the effect of CA-SIIF on secretion of other cytokines by monocytes is unknown, and detailed characterization of this factor has not been performed. 相似文献65.
Andrew B. Stein Todd K. Fuller Laurie L. Marker 《Biodiversity and Conservation》2008,17(14):3579-3587
In northcentral Namibia, Waterberg Plateau Park (WPP) is a protected area that acts as a refuge for rare and endangered species,
while the farmlands surrounding the Park are managed for livestock production, but support populations of wildlife for game
farming, trophy hunting, and conservation. During June–October 2006, camera-traps were set within and surrounding WPP to assess
leopard (Panthera pardus) density (n = 19 camera stations and 946 camera-trap-nights). Fortuitously, photographic results (2,265 photos of identifiable mammal
(n = 37) and bird (n = 25) species) allowed us to assess aspects of species diversity and differences among the Park, the farmland areas along
the Waterberg Plateau escarpment, and the flatlands surrounding the escarpment. Species composition among the three areas
was markedly different, and made sense with respect to differences in habitat and management features. Camera-trapping efforts,
although intended for a narrow purpose, may also provide a rather robust record of differences in mammal and bird diversity
in adjacent habitats and can be incorporated into long-term monitoring programs. 相似文献
66.
Brett M. Bennett 《Journal of the history of biology》2011,44(1):125-145
Scholars studying the globalization of Australian trees have previously emphasized the rapid natural propagation of Australian
trees outside of their native habitats, believing their success to be a reversal of “ecological imperialism” from the “new
world” to the “old world.” This article argues that the expansion of Australian trees should not be viewed as a biological
phenomenon, but as the result of a long-term attempt by powerful states and state-sponsored scientists to select and breed
Australian species that could grow in a variety of climates and ecological conditions. Five non-biological factors largely
determined the success of these attempts to grow Australian trees: the abundance or paucity of natural forests, state power,
the amount of scientific research directed to planting Australian trees, the cost of labor, and the ability to utilize hardwood
timbers and bark. This paper compares the use of Australian trees in Australia, India, and South Africa to demonstrate that
biology was not the determining factor in the long-term success of many Australian genera and species. 相似文献
67.
Research has revealed that most chlorophyllous explants/plants in vitro have the ability to grow photoautotrophically (without
sugar in the culture medium), and that the low or negative net photosynthetic rate of plants in vitro is not due to poor photosynthetic
ability, but to the low CO2 concentration in the air-tight culture vessel during the photoperiod. Moreover, numerous studies have been conducted on improving
the in vitro environment and investigating its effects on growth and development of cultures/plantlets on nearly 50 species
since the concept of photoautotrophic micropropagation was developed more than two decades ago. These studies indicate that
the photoautotrophic growth in vitro of many plant species can be significantly promoted by increasing the CO2 concentration and light intensity in the vessel, by decreasing the relative humidity in the vessel, and by using a fibrous
or porous supporting material with high air porosity instead of gelling agents such as agar. This paper reviews the development
and characteristics of photoautotrophic micropropagation systems and the effects of environmental conditions on the growth
and development of the plantlets. The commercial applications and the perspective of photoautotrophic micropropagation systems
are discussed. 相似文献
68.
Background
Interaction of a drug or chemical with a biological system can result in a gene-expression profile or signature characteristic of the event. Using a suitably robust algorithm these signatures can potentially be used to connect molecules with similar pharmacological or toxicological properties by gene expression profile. Lamb et al first proposed the Connectivity Map [Lamb et al (2006), Science 313, 1929–1935] to make successful connections among small molecules, genes, and diseases using genomic signatures. 相似文献69.
Role of Thidiazuron (TDZ) in inducing adventitious organogenesis in Pongamia was studied. TDZ at different concentrations (0, 0.45, 2.27, 4.54, 6.71, 9.08, 11.35, 13.12 and 22.71 μM) were used for induction
of caulogenic bud formation in deembryonated cotyledon explants. Each cotyledon was cut into three segments and identified
as proximal, middle and distal. Duration of TDZ exposure, influence of the segment and orientation of the explant were studied.
TDZ at 11.35 μM concentration was optimum for the induction of shoots and rapid elongation. Shoots induced at higher concentration
elongated after several passages in growth regulator free medium, thereby extending the period of differentiation. Exposure
of the explant for 20 days yielded more number of buds than 10 days. Proximal segment of the cotyledon was more responsive.
Contact of abaxial surface in the medium was more effective and generated more buds than the adaxial side. Buds differentiated
and elongated on transfer to MS basal medium for 8–12 passages of 15 days each. Rooting and elongation of shoots was achieved
in charcoal supplemented half-strength MS medium. Rooted plantlets survived on transfer to sand soil mixture. The plants were
hardened and transferred to green house. This is the first report on in vitro regeneration of Pongamia pinnata via adventitious organogenesis using TDZ. This protocol may find application in studies in genetic transformation, isolation
of somaclonal variants and in induction of mutants. It also provides a system to study the inhibitory role of TDZ on shoot
differentiation. 相似文献
70.
Caio Maximino 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2008,194(11):939-944
The fast-start is an ecologically relevant behavior pattern in fishes. The present article analyses the distribution of five
continuous kinematic traits (latency for response initiation, time to maximum angular velocity, time to maximum displacement
velocity, maximum angular velocity, and maximum displacement velocity) in eight of the eleven species described in Eaton (66:65–81,
1977). Phylogenetic generalized least square estimation of ancestor states demonstrated evolutionary changes in maximum angular
velocity and maximum displacement velocity, consistent with species differences in the same variables. These changes in maximum
velocity are also correlated (phylogenetically independent contrasts) with the mean body sizes of all species, pointing to
the possibility that body size was an evolutionary constraint on maximum velocities. The conservation of the other traits
suggest that they are mainly constrained by neural control, and a trade-off between neural and body size-constraints is proposed
ex hypothesi.
An erratum to this article can be found at 相似文献