全文获取类型
收费全文 | 84718篇 |
免费 | 5413篇 |
国内免费 | 5063篇 |
专业分类
化学 | 40193篇 |
晶体学 | 612篇 |
力学 | 7638篇 |
综合类 | 1002篇 |
数学 | 18326篇 |
物理学 | 27423篇 |
出版年
2024年 | 104篇 |
2023年 | 716篇 |
2022年 | 1345篇 |
2021年 | 1988篇 |
2020年 | 1981篇 |
2019年 | 1958篇 |
2018年 | 1750篇 |
2017年 | 2135篇 |
2016年 | 2660篇 |
2015年 | 2018篇 |
2014年 | 3072篇 |
2013年 | 5610篇 |
2012年 | 4039篇 |
2011年 | 4009篇 |
2010年 | 3335篇 |
2009年 | 4880篇 |
2008年 | 5079篇 |
2007年 | 5734篇 |
2006年 | 4797篇 |
2005年 | 4008篇 |
2004年 | 3610篇 |
2003年 | 3598篇 |
2002年 | 3677篇 |
2001年 | 2820篇 |
2000年 | 2712篇 |
1999年 | 2352篇 |
1998年 | 2250篇 |
1997年 | 1527篇 |
1996年 | 1449篇 |
1995年 | 1307篇 |
1994年 | 1298篇 |
1993年 | 1000篇 |
1992年 | 1034篇 |
1991年 | 772篇 |
1990年 | 724篇 |
1989年 | 522篇 |
1988年 | 462篇 |
1987年 | 391篇 |
1986年 | 337篇 |
1985年 | 336篇 |
1984年 | 324篇 |
1983年 | 181篇 |
1982年 | 259篇 |
1981年 | 218篇 |
1980年 | 147篇 |
1979年 | 194篇 |
1978年 | 129篇 |
1977年 | 99篇 |
1976年 | 61篇 |
1973年 | 41篇 |
排序方式: 共有10000条查询结果,搜索用时 749 毫秒
121.
122.
123.
The diffusion of the anti-microbial chlorhexidine digluconate (CHG) has been studied in C. albicans biofilms by time-of-flight secondary-ion mass spectrometry (TOF-SIMS). C. albicans has been shown to become resistant to common anti-microbial agents, including CHG, when growing as a biofilm. Mass transport resistance within biofilms has commonly been suggested as a resistance mechanism, but measurement of transport for most anti-microbial agents in biofilms has proven extremely difficult because of the heterogeneity of the biofilms and the difficulty in detecting these agents within an intact biofilm. In this study, TOF-SIMS has been used to study the transport of CHG and glucose in a frozen hydrated biofilm. The TOF-SIMS images reveal a progression of CHG from the top of the biofilm to its base with time. Images suggest that there are channels within the biofilm and show preferential binding of CHG to cellular components of the biofilm. Additionally, both living and dead cells can be identified in the TOF-SIMS images by the sequestration of K+ and the presence of cell markers. This study demonstrates that TOF-SIMS has the unique potential to simultaneously observe the presence of an antimicrobial agent, concentration of nutrients, and the viability of the cell population. 相似文献
124.
125.
M. Brando N. Büttgen V. Fritsch J. Hemberger H. Kaps H.-A. Krug von Nidda M. Nicklas K. Pucher W. Trinkl A. Loidl E.W. Scheidt M. Klemm S. Horn 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,25(3):289-298
We present susceptibility, microwave resistivity, NMR and heat-capacity results for Li1-xZnx(V1-yTiy)2O4 with 0 ?
x
? 0.3 and 0 ?
y
? 0.3. For all doping levels the susceptibility curves can be fitted with a Curie-Weiss law. The paramagnetic Curie-Weiss temperatures
remain negative with an average value close to that of the pure compound Θ≈ - 36 K. Spin-glass anomalies are observed in the susceptibility, heat-capacity and NMR measurements for both type of dopants.
From the temperature dependence of the spin-lattice relaxation rate we found critical-dynamic behavior in the Zn doped compounds
at the freezing temperatures. For the Ti-doped samples two successive freezing transitions into disordered low-temperature
states can be detected. The temperature dependence of the heat capacity for Zn-doped compounds does not resemble that of canonical
spin glasses and only a small fraction of the total vanadium entropy is frozen at the spin-glass transitions. For pure LiV2O4 the spin-glass transition is completely suppressed. The temperature dependence of the heat capacity for LiV2O4 can be described using a nuclear Schottky contribution and the non-Fermi liquid model, appropriate for a system close to
a spin-glass quantum critical point. Finally an (
x
/
y
,
T
)-phase diagram for the low-doping regime is presented.
Received 16 March 2001 and Received in final form 30 October 2001 相似文献
126.
G. Tiana M.H. Jensen K. Sneppen 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(1):135-140
A feedback mechanism that involves the proteins p53 and mdm2, induces cell death as a controlled response to severe DNA damage.
A minimal model for this mechanism demonstrates that the response may be dynamic and connected with the time needed to translate
the mdm2 protein. The response takes place if the dissociation constant k between p53 and mdm2 varies from its normal value. Although it is widely believed that it is an increase in k that triggers the response, we show that the experimental behaviour is better described by a decrease in the dissociation
constant. The response is quite robust upon changes in the parameters of the system, as required by any control mechanism,
except for few weak points, which could be connected with the onset of cancer.
Received 8 May 2002 / Received in final form 9 July 2002 Published online 17 September 2002 相似文献
127.
128.
129.
130.
Patrick Dehornoy 《Algebra Universalis》2002,48(2):223-248
We solve the word problem of the identity x(yz) = (xy)(yz) by investigating a certain group describing the geometry of that identity. We also construct a concrete realization of the
one-generated free algebra relative to the above identity.
Received March 23, 2001; accepted in final form July 6, 2002. 相似文献