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991.
刘方 孙兴国 李启威 葛万刚 李浩 刘艳玲 慈政 陈升平 宋桂芹 王桂芝 谭晓越 崔闫 张也 朱嘉宝 李银俊 邓维 黄燕 马铭欣 陈荣 邹昱馨 台文琦 徐凡 石超 《中国应用生理学杂志》2021,37(1):9-14
目的: 为探讨新生儿自主呼吸产生机制,前文已对新生儿出生后自主呼吸开始前脐带动静脉氧气和二氧化碳差值进行了人群组间分析;而本部分则对相关信息进行个体化分析。方法: 在产前经所有胎儿父母签署知情同意书,新生儿出生后还没有呼吸之前在脐带动脉和脐带静脉分别连续逐搏取血,仅有3例同时采集到Pua和Puv血液样本进行血气分析测定,计算分析脐带静脉和脐带动脉的异同和动态变化。结果: 虽然准备了数十产妇,但仅有3例同时采集到Pua和Puv血液样本,同一时间的PuvO2显著高于PuaO2(P均<0.01),平均相差(24.17±7.09) mmHg;而PuvCO2显著低于PuaCO2(P均<0.01),平均相差(-7.67±3.70) mmHg。在同一时间的Puv-uaO2显著高于Puv-uaCO2(P<0.05)。结论: 新生儿出生后自主呼吸前,全部氧气供应由脐带静脉运输,只要胎盘开始剥离则新生儿的PuaO2随时间(心跳次数)逐渐降低,当PuaO2达到触发呼吸阈值(最低值)诱发第一次吸气开始其自主呼吸。 相似文献
992.
Microbial modification of naturally occurring materials is one of the efficient ways to add new values to them. Hydroxylation
of free unsaturated fatty acids by microorganism is a good example of those modifications. Among microbial strains studied
for that purpose, a new bacterial isolate Pseudomonas aeruginosa PR3 has been well studied to produce several hydroxy fatty acids from different unsaturated fatty acids. Of those hydroxy
fatty acids, 7,10-dihydroxy-8(E)-octadecenoic acid (DOD) was efficiently produced from oleic acid by strain PR3. However, it was highly plausible to use
vegetable oil containing oleic acid rather than free oleic acid as a substrate for DOD production by strain PR3. In this study,
we firstly tried to use olive oil containing high content of oleic acid as a substrate for DOD production. DOD production
from olive oil was confirmed by structural determination with GC, TLC, and GC/MS analysis. DOD production yield from olive
oil was 53.5%. Several important environmental factors were also tested. Galactose and glutamine were optimal carbon and nitrogen
sources, and magnesium ion was critically required for DOD production from olive oil. Results from this study demonstrated
that natural vegetable oils containing oleic acid could be used as efficient substrate for the production of DOD by strain
PR3. 相似文献
993.
994.
用蛋白质工程方法改变葡萄糖异构酶最适pH和最适温度 总被引:3,自引:2,他引:3
用寡核苷酸诱导的定点突变方法构建了葡萄糖异构酶基因的突变体(N184D和A198C)。含突变体的重组质粒pTKD-GI1(N184D)和pTKD-GI2(A198c)在E.coliK38菌株中表达,用DEAE-Sepharose FF和Sephacryl S-300HR柱层析分离纯化突变酶。与野生型葡萄糖异构酶比较实验表明:(1)突变酶N184D的最适pH值下降了1个单位;等电点下降了0.6个单位 相似文献
995.
996.
Daniël C. Koppenol Fred J. Vermolen Frank B. Niessen Paul P. M. van Zuijlen Kees Vuik 《Biomechanics and modeling in mechanobiology》2017,16(1):15-32
A continuum hypothesis-based model is presented for the simulation of the formation and the subsequent regression of hypertrophic scar tissue after dermal wounding. Solely the dermal layer of the skin is modeled explicitly and it is modeled as a heterogeneous, isotropic and compressible neo-Hookean solid. With respect to the constituents of the dermal layer, the following components are selected as primary model components: fibroblasts, myofibroblasts, a generic signaling molecule and collagen molecules. A good match with respect to the evolution of the thickness of the dermal layer of scars between the outcomes of simulations and clinical measurements on hypertrophic scars at different time points after injury in human subjects is demonstrated. Interestingly, the comparison between the outcomes of the simulations and the clinical measurements demonstrates that a relatively high apoptosis rate of myofibroblasts results in scar tissue that behaves more like normal scar tissue with respect to the evolution of the thickness of the tissue over time, while a relatively low apoptosis rate results in scar tissue that behaves like hypertrophic scar tissue with respect to the evolution of the thickness of the tissue over time. Our ultimate goal is to construct models with which the properties of newly generated tissues that form during wound healing can be predicted with a high degree of certainty. The development of the presented model is considered by us as a step toward their construction. 相似文献
997.
998.
999.
In the dysfunctional splice variant TRPM2-ΔN, a stretch of 20 amino acids (aa 537–556) is missing within the N-terminal cytosolic
tail of the cation channel TRPM2. The ΔN-stretch overlaps with two IQ-like calmodulin-binding domains. Moreover, it contains
two PxxP motifs implicated in protein–protein interactions. Here, we constructed variants to test whether any of these motifs
may explain why TRPM2-ΔN does not respond to stimulation with either ADP ribose or hydrogen peroxide. Each of the two IQ-motifs
could be removed without loss of channel function. Similarly, deletion of either one or both PxxP motifs had no effect. Moreover,
the single point mutation D543E associated with bipolar disorder does not change the activation of TRPM2. We conclude that
no functional role can be attributed to any of the structural motifs within the ΔN-stretch that may be a spacer segment for
other functional sites in the N terminus. 相似文献
1000.
The conversion of and toxic effects exerted by several mono- and dihalogenated C1 and C2 compounds on cultures of Xanthobacter autotrophicus GJ10 growing on 1,2-dichloroethane were investigated. Bromochloromethane, dibromomethane and 1-bromo-2-chloroethane were
utilized by strain GJ10 in batch culture as a cosubstrate and sole carbon source. The rate of degradation of dihalomethanes
by whole cells was lower than that of 1,2-dichloroethane, but a significant increase of the rate of dihalomethane biodegradation
was observed when methanol or ethanol were added as a cosubstrate. Products of the degradation of several tested compounds
by haloalkane dehalogenase were analyzed and a new metabolic pathway based on hydrolytic conversion to formaldehyde was proposed
for the dihalomethanes. Strain GJ10 growing on 1,2-dichloroethane converted 2-fluoroethanol and 1-chloro-2-fluoroethane to
2-fluoroacetate, which was tolerated up to a concentration of 2.5 mM. On the basis of the results from batch cultures an inert
(dichloromethane), a growth-supporting (dibromomethane) and a toxic (1,2-dibromoethane) compound were selected for testing
their effects on a continuous culture of strain GJ10 growing on 1,2-dichloroethane. The compounds were added as pulses to
a steady-state chemostat and the response of the culture was followed. The effects varied from a temporary decrease in cell
density for dibromomethane to severe toxicity and culture washout with 1,2-dibromoethane. Our results extend the spectrum
of halogenated C1 and C2 compounds that are known to be degraded by strain GJ10 and provide information on toxic effects and
transformation of compounds not serving as a carbon source for this bacterium. 相似文献