全文获取类型
收费全文 | 2711篇 |
免费 | 173篇 |
专业分类
2884篇 |
出版年
2022年 | 13篇 |
2021年 | 30篇 |
2020年 | 15篇 |
2019年 | 22篇 |
2018年 | 40篇 |
2017年 | 28篇 |
2016年 | 34篇 |
2015年 | 75篇 |
2014年 | 70篇 |
2013年 | 161篇 |
2012年 | 107篇 |
2011年 | 130篇 |
2010年 | 70篇 |
2009年 | 81篇 |
2008年 | 150篇 |
2007年 | 136篇 |
2006年 | 121篇 |
2005年 | 99篇 |
2004年 | 133篇 |
2003年 | 119篇 |
2002年 | 139篇 |
2001年 | 74篇 |
2000年 | 98篇 |
1999年 | 67篇 |
1998年 | 37篇 |
1997年 | 35篇 |
1996年 | 28篇 |
1995年 | 33篇 |
1994年 | 19篇 |
1993年 | 30篇 |
1992年 | 70篇 |
1991年 | 56篇 |
1990年 | 49篇 |
1989年 | 71篇 |
1988年 | 70篇 |
1987年 | 44篇 |
1986年 | 33篇 |
1985年 | 31篇 |
1984年 | 22篇 |
1983年 | 19篇 |
1982年 | 28篇 |
1981年 | 15篇 |
1980年 | 13篇 |
1979年 | 14篇 |
1978年 | 17篇 |
1977年 | 13篇 |
1976年 | 16篇 |
1974年 | 13篇 |
1973年 | 14篇 |
1969年 | 20篇 |
排序方式: 共有2884条查询结果,搜索用时 3 毫秒
121.
The low molecular weight carbohydrate compositions of the seeds of 29 species ofVicia, namelyV. amoena, V. amurensis, V. bifolia, V. dumetorum, V. fauriei, V. japonica, V. nipponica, V. pisiformis, V. pseudo-orobus,
V. sylvatica, V. unijuga, V. venosa, V. cassubica, V. orobus, V. cracca agg.,V. hirsuta, V. villosa agg.,V. tetrasperma,V. oroboides, V. sepium, V. cuspidata, V. grandiflora, V. lathyloides, V. sativa agg.,V. bithynica, V. faba, V. narbonensis, V. hybrida andV. lutea were determined by gas liquid chromatography. The carbohydrate compositions were found to be species-specific. Principal
component analysis of the carbohydrate composition data showed that these species can be divided into three groups. Although,
as far as the examined species were concerned, these groups were not correlated with the known subgenera, significant correlation
between the groups and the known sections was detected in the subgenusVicia. The carbohydrate composition character would be important to clarify the relationships among closely related taxa of the
genusVicia. 相似文献
122.
Data base management is needed in the whole industries, particularly in the fermentation industry, whose jobs are tedious yet require carefulness. The most important problem in the database system is not how to collect many informations, but how to handle the meaningful ones.The authors have recently developed an on-line monitoring and control system for the fermentation processes in co-operation with Fuji Facom Co. Ltd. and Komatsugawa Chemical Engineering Co. Ltd.This system enables us to measure directly those concentrations in fermentation systems which have been measured by offline so far, such as cell mass, substrate and metabolic products. The physiological activities of a microorganism, such as specific rate of cellular growth, that of substrate consumption, that of metabolites production, etc., became estimable precisely by eliminating the effect of noises.By enlarging the function of our monitoring and control system, we have developed a database system which is applicable in job scheduling not only in the laboratory but also in the production line, in automatic resource allocation and fault analyses of the fermentation processes. 相似文献
123.
The blasticidin S resistance gene (bsr) selectable in a single copy state in the Bacillus subtilis chromosome 总被引:8,自引:0,他引:8
The blasticidin S resistance gene (bsr), originally isolated from Bacillus cereus, was studied in Bacillus subtilis. It was found that a 617 bp fragment including the intact bsr gene and its 5' flanking region could confer BS resistance on B. subtilis when integrated in its chromosome, even in a single copy state. The construction of a bsr gene cassette and its practical application as a novel selection marker for B. subtilis are reported. 相似文献
124.
Ichthyological Research - Two types of ophichthid larvae collected from Japanese coastal waters around Kyushu and Shikoku were identified by DNA barcoding as Ophichthus celebicus (Bleeker 1856) and... 相似文献
125.
Sayuki Iijima Kentaro Matsuura Tsunamasa Watanabe Koji Onomoto Takashi Fujita Kyoko Ito Etsuko Iio Tomokatsu Miyaki Kei Fujiwara Noboru Shinkai Atsunori Kusakabe Mio Endo Shunsuke Nojiri Takashi Joh Yasuhito Tanaka 《PloS one》2015,10(2)
The levels of expression of interferon-stimulated genes (ISGs) in liver are associated with response to treatment with pegylated interferon (PEG-IFN) plus ribavirin (RBV). However, associations between the responses of ISGs to IFN-based therapy and treatment efficacy or interleukin-28B (IL28B) genotype have not yet been determined. Therefore, we investigated the early responses of ISGs and interferon-lambdas (IFN-λs) in peripheral blood mononuclear cells (PBMCs) during PEG-IFN/RBV plus NS3/4 protease inhibitor (PI) therapy. We prospectively enrolled 50 chronic hepatitis C patients with HCV genotype 1, and collected PBMCs at baseline, 8 and 24 h after the initial administration of PEG-IFN/RBV/PI. Levels of mRNAs for selected ISGs and IFN-λs were evaluated by real-time PCR. All 31 patients with a favorable IL28B genotype and 13 of 19 with an unfavorable genotype achieved sustained virological responses (SVR). Levels of mRNA for A20, SOCS1, and SOCS3, known to suppress antiviral activity by interfering with the IFN signaling pathway, as well as IRF1 were significantly higher at 8 h in patients with an unfavorable IL28B genotype than in those with a favorable one (P = 0.007, 0.026, 0.0004, 0.0006, respectively), especially in the non-SVR group. Particularly, the fold-change of IRF1 at 8 h relative to baseline was significantly higher in non-SVR than in SVR cases with an unfavorable IL28B genotype (P = 0.035). In conclusion, levels of several mRNAs of genes suppressing antiviral activity in PBMCs during PEG-IFN/RBV/PI differed according to IL28B genotypes, paralleling treatment efficacy. 相似文献
126.
Whaldener Endo Carlos A. Peres Edith Salas Sandra Mori Jose-Luis Sanchez-Vega Glenn H. Shepard Victor Pacheco Douglas W. Yu 《Biotropica》2010,42(2):251-261
Manu National Park of southern Peru is one of the most renowned protected areas in the world, yet large-bodied vertebrate surveys conducted to date have been restricted to Cocha Cashu Biological Station, a research station covering <0.06 percent of the 1.7 Mha park. Manu Park is occupied by >460 settled Matsigenka Amerindians, 300–400 isolated Matsigenka, and several, little-known groups of isolated hunter–gatherers, yet the impact of these native Amazonians on game vertebrate populations within the park remains poorly understood. On the basis of 1495 km of standardized line-transect censuses, we present density and biomass estimates for 23 mammal, bird, and reptile species for seven lowland and upland forest sites in Manu Park, including Cocha Cashu. We compare these estimates between hunted and nonhunted sites within Manu Park, and with other Neotropical forest sites. Manu Park safeguards some of the most species-rich and highest biomass assemblages of arboreal and terrestrial mammals ever recorded in Neotropical forests, most likely because of its direct Andean influence and high levels of soil fertility. Relative to Barro Colorado Island, seed predators and arboreal folivores in Manu are rare, and generalist frugivores specializing on mature fruit pulp are abundant. The impact of such a qualitative shift in the vertebrate community on the dynamics of plant regeneration, and therefore, on our understanding of tropical plant ecology, must be profound. Despite a number of external threats, Manu Park continues to serve as a baseline against which other Neotropical forests can be gauged. Abstract in Spanish is available at http://www.blackwell-synergy.com/loi/btp . 相似文献
127.
128.
Sato Y Goto Y Sato S Endo S Sohara Y 《American journal of physiology. Lung cellular and molecular physiology》2004,286(1):L143-L148
The use of granulocyte colony stimulating factor (G-CSF) for recovery from neutropenia has been established; however, acute lung injury due to G-CSF-induced polymorphonuclear leukocyte (PMN) activation is a serious complication. This study was designed to compare the activation of PMN with single bolus administration and continuous administration of G-CSF. Healthy volunteers (age 33.8 +/- 1.4 yr; n = 6) received a single bolus injection of 50 microm/m2 of G-CSF (SI; n = 6) or continuous subcutaneous injection of 50 microm/m2 of G-CSF for 24 h (CI; n = 6) and were followed for 48 h. Circulating leukocyte counts, markers of activation on PMN, and circulating levels of G-CSF, IL-6, and PMN elastase were measured. SI rapidly increased serum G-CSF levels, which peaked at 4 h, whereas CI gradually increased G-CSF levels, which remained at a steady level from 8 to 24 h. SI caused a rapid decrease in PMN counts at 0.5 h followed by sustained increase to peak at 12 h. CI gradually increased PMN counts, which peaked at 24 h, but the peak values were not significantly different between the groups. SI-induced activation of PMN, which was characterized by increased expression of CD11b, decreased expression of L-selectin, and increased F-actin content, led to increases in serum IL-6 and PMN elastase level. Such changes were all attenuated with CI (P < 0.05). We conclude that continuous subcutaneous injection of G-CSF resulted in a marrow response similar to that to a single injection but yielded reduced PMN activation. 相似文献
129.
Mitsuomi?Shimazakimitujin@fish.hokudai.ac.jp; MY myabe@fish.hokudai.ac.jp" title="MS mitujin@fish.hokudai.ac.jp; MY myabe@fish.hokudai.ac.jp" itemprop="email" data-track="click" data-track-action="Email author" data-track-label="">Email author Hiromitsu?Endo Mamoru?Yabe 《Ichthyological Research》2004,51(2):120-125
Halieutopsis bathyoreos Bradbury, 1988 (Lophiiformes: Ogcocephalidae), previously described only on the basis of the holotype (62.6mm in standard length) from the central North Pacific, is redescribed on the basis of the holotype and six additional specimens (41.2–68.7mm in standard length) collected from the western South Pacific, off Papua New Guinea, and the western North Pacific, including the Japanese Archipelago. Halieutopsis bathyoreos is distinguished from its congeners by having a shelflike rostrum extending anteriorly well beyond the mouth, a dorsal escal lobe slightly bisected ventrally, an illicial cavity square in outline and completely visible in ventral view, and lacking tubercles on the ventral surface of the disk. The following characters are newly added to the diagnoses of this species: rostrum width 21–29% of head length, tubercles on the dorsal surface of the disk about half the diameter of those on the lateral margin, and 13–15 large lateral-line scales on the tail. 相似文献
130.
We investigated GroEL substrates from Bacillus subtilis 168 using the single-ring mutant of B. subtilis GroEL. We identified 28 candidates for GroEL substrates, of which Spo0B, Ald, Eno, SpoIIP, and FbaA were involved in spore formation, and Rnc, Tuf, Eno, Tsf, and FbaA were essential for B. subtilis growth. As observed at the protein level, the amount of SpoIIP interaction with GroEL increased at 3 h after initiation of sporulation. 相似文献