全文获取类型
收费全文 | 39391篇 |
免费 | 959篇 |
国内免费 | 269篇 |
专业分类
化学 | 26503篇 |
晶体学 | 159篇 |
力学 | 809篇 |
综合类 | 2篇 |
数学 | 7584篇 |
物理学 | 5562篇 |
出版年
2022年 | 218篇 |
2021年 | 308篇 |
2020年 | 440篇 |
2019年 | 412篇 |
2018年 | 338篇 |
2017年 | 339篇 |
2016年 | 778篇 |
2015年 | 792篇 |
2014年 | 881篇 |
2013年 | 1796篇 |
2012年 | 1676篇 |
2011年 | 1999篇 |
2010年 | 1181篇 |
2009年 | 1027篇 |
2008年 | 1775篇 |
2007年 | 1775篇 |
2006年 | 1864篇 |
2005年 | 1684篇 |
2004年 | 1594篇 |
2003年 | 1372篇 |
2002年 | 1329篇 |
2001年 | 654篇 |
2000年 | 594篇 |
1999年 | 519篇 |
1998年 | 509篇 |
1997年 | 571篇 |
1996年 | 553篇 |
1995年 | 502篇 |
1994年 | 542篇 |
1993年 | 503篇 |
1992年 | 478篇 |
1991年 | 451篇 |
1990年 | 408篇 |
1989年 | 417篇 |
1988年 | 401篇 |
1987年 | 362篇 |
1986年 | 374篇 |
1985年 | 595篇 |
1984年 | 574篇 |
1983年 | 443篇 |
1982年 | 518篇 |
1981年 | 482篇 |
1980年 | 531篇 |
1979年 | 457篇 |
1978年 | 495篇 |
1977年 | 507篇 |
1976年 | 400篇 |
1975年 | 361篇 |
1974年 | 336篇 |
1973年 | 345篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
43.
After a discussion of a space of test functions and the corresponding space of distributions, a family of Banach spaces (B, ∥ ∥B) in standard situation is described. These are spaces of distributions having a pointwise module structure and also a module structure with respect to convolution. The main results concern relations between the different spaces associated to B established by means of well-known methods from the theory of Banach modules, among them B0 and , the closure of the test functions in B and the weak relative completion of B, respectively. The latter is shown to be always a dual Banach space. The main diagram, given in Theorem 4.7, gives full information concerning inclusions between these spaces, showing also a complete symmetry. A great number of corresponding formulas is established. How they can be applied is indicated by selected examples, in particular by certain Segal algebras and the Ap-algebras of Herz. Various further applications are to be given elsewhere. 相似文献
44.
Hans Grauert 《Mathematische Zeitschrift》1989,200(2):149-168
Ohne ZusammenfassungHerrn E. Heinz zum 65. Geburtstag gewidmet 相似文献
45.
Ohne ZusammenfassungDiese Arbeit wurde während eines Aufenthaltes von Schmidt in der Bundesrepublik Deutschland als Preisträger der Alexander von Humboldt-Stiftung geschrieben. 相似文献
46.
Butyltins were analyzed in waters from California river and lake marinas and were detected at the part per trillion (ppt) level in most locations. The tributyltin:dibutyltin (TBT/DBT) ratios in the fresh waters were similar to those in their saline counterparts indicating like rates of degradation in the two salinity regimes. 相似文献
47.
This study analyzes the economics of transshipping biomass from truck to train in a North American setting. Transshipment
will only be economic when the cost per unit distance of a second transportation mode is less than the original mode. There
is an optimum number of transshipment terminals which is related to biomass yield. Transshipment incurs incremental fixed
costs, and hence there is a minimum shipping distance for rail transport above which lower costs/km offset the incremental
fixed costs. For transport by dedicated unit train with an optimum number of terminals, the minimum economic rail shipping
distance for straw is 170 km, and for boreal forest harvest residue wood chips is 145 km. The minimum economic shipping distance
for straw exceeds the biomass draw distance for economically sized centrally located power plants, and hence the prospects
for rail transport are limited to cases in which traffic congestion from truck transport would otherwise preclude project
development. Ideally, wood chip transport costs would be lowered by rail transshipment for an economically sized centrally
located power plant, but in a specific case in Alberta, Canada, the layout of existing rail lines precludes a centrally located
plant supplied by rail, whereas a more versatile road system enables it by truck. Hence for wood chips as well as straw the
economic incentive for rail transport to centrally located processing plants is limited. Rail transshipment may still be preferred
in cases in which road congestion precludes truck delivery, for example as result of community objections. 相似文献
48.
49.
Hans Weber 《Order》2007,24(4):249-276
We study lattice theoretical properties of lattices of uniformities such as modularity, distributive laws and the existence
of (relative) complements. For this the concepts of permutable uniformities (see Definition 3.1) and independent uniformities
(see Definition 4.1) are important. Moreover, we show that e.g. the lattice of all lattice uniformities on a lattice L is a closed sublattice of the lattice of all uniformities on L. 相似文献
50.
In a structural measurement error model the structural quasi-score (SQS) estimator is based on the distribution of the latent regressor variable. If this distribution is misspecified, the SQS estimator is (asymptotically) biased. Two types of misspecification are considered. Both assume that the statistician erroneously adopts a normal distribution as his model for the regressor distribution. In the first type of misspecification, the true model consists of a mixture of normal distributions which cluster around a single normal distribution, in the second type, the true distribution is a normal distribution admixed with a second normal distribution of low weight. In both cases of misspecification, the bias, of course, tends to zero when the size of misspecification tends to zero. However, in the first case the bias goes to zero in a flat way so that small deviations from the true model lead to a negligible bias, whereas in the second case the bias is noticeable even for small deviations from the true model. 相似文献